add Home entry point with introduction journey, CMEM-8370

New users had no starting point: the homepage was a tile grid only, the
tiles did not follow the menu bar order, and Getting Started described
the product without introducing it.

- add a Home tab with house icon as first menu entry and first tile
- reorder the homepage tiles to match the menu bar, point Release Notes
  to 26.2 and drop the Getting Started tile
- continue the homepage with "What is eccenca Corporate Memory?",
  including the 3-minute video, and show its table of contents
- add the introduction pages What is a knowledge graph?, Semantic Web
  basics, At a glance, Get access and See it in the product, with
  diagrams and screenshots
- hide the empty table of contents on the Develop overview

Verified against CMEM v26.2.2 (Explore) for the Semantic Web basics
and Shape views screenshots.

Author: annamakor

docs/.pages

@@ -1,5 +1,8 @@
 ---
 nav:
+    - Home:
+          - index.md
+          - introduction
     - Build: build
     - Explore: explore-and-author
     - Consume: consume
@@ -9,4 +12,3 @@ nav:
     - Develop: develop
     - Release Notes: release-notes
     - Tutorials: tutorials
-

docs/develop/index.md

@@ -1,5 +1,7 @@
 ---
 icon: material/star-outline
+hide:
+  - toc
 ---
 # Develop
 

docs/graph-insights-suppliers-products-countries.png

@@ -1,31 +1,18 @@
 ---
+title: "Welcome to the eccenca Corporate Memory documentation"
+icon: material/home
 comments: false
-hide:
-  - toc
-  - navigation
 ---
 
 # Welcome to the eccenca Corporate Memory documentation
 
 <div class="grid cards" markdown>
 
-- :material-calendar: [Release Notes](release-notes/2024/corporate-memory-24-3/index.md)
+- :material-home: [Home](#what-is-eccenca-corporate-memory)
 
     ---
 
-    Documentation of changes and enhancements for each version.
-
-- :material-list-status: [Tutorials](tutorials/index.md)
-
-    ---
-
-    Learn by example and step-by-step guidelines to achieve a concrete goal fast.
-
-- :material-arrow-right-thick: [Getting Started](getting-started/index.md)
-
-    ---
-
-    This page describes how to work with Corporate Memory and shortly outlines all functionalities of the user interface.
+    New to eccenca Corporate Memory? Start here: what the product is for, how it is structured, and how to get access.
 
 - :material-star: [Build](build/index.md)
 
@@ -69,4 +56,156 @@ hide:
 
     Extend Corporate Memory with custom plugins and packages, and access it programmatically through the Python, Java and REST APIs.
 
+- :material-calendar: [Release Notes](release-notes/2026/corporate-memory-26-2/index.md)
+
+    ---
+
+    Documentation of changes and enhancements for each version.
+
+- :material-list-status: [Tutorials](tutorials/index.md)
+
+    ---
+
+    Learn by example and step-by-step guidelines to achieve a concrete goal fast.
+
 </div>
+
+## What is eccenca Corporate Memory?
+
+Corporate Memory connects data that lives in separate systems into one meaningful whole, a knowledge graph.
+It keeps that whole usable as the systems and the business around it change.
+
+Prefer to watch?
+The video [eccenca Corporate Memory in 3 minutes](https://www.youtube.com/watch?v=Lb0zpH9oLMM){target=_blank} shows what Corporate Memory is for, without a product demo.
+
+[![Video eccenca Corporate Memory in 3 minutes on YouTube: a knowledge graph answering which products are affected if Kessler GmbH fails](video-corporate-memory-in-3-minutes.jpg){ class="bordered off-glb" width="60%" }](https://www.youtube.com/watch?v=Lb0zpH9oLMM){target=_blank}
+
+Reading time: 4 minutes.
+No prior knowledge is required.
+The following sections explain what the product is for, not how to use it.
+
+### A familiar problem
+
+A supplier has just gone out of business.
+Someone in purchasing needs to know which products are affected.
+
+The answer exists.
+But the product is called `P-10045` in the ERP system, `PRD_10045_A` in the PLM system and `45100-XX` in the supplier portal.
+Each system is right on its own terms, and none of them knows about the others.
+So the answer is put together by hand, takes days, and is out of date by the time anyone acts on it.
+
+Most organizations do not have a data shortage.
+They have a connection problem.
+
+### What eccenca Corporate Memory does
+
+![Left: three systems with three names for the same product. Right: the same product, connected by named relationships.](three-systems-one-product.png){ class="bordered" }
+
+Corporate Memory gives the context of the data a place to live.
+
+It reads data from existing systems and expresses it as a knowledge graph: things, and the named relationships between them.
+This product is made at this plant.
+This plant is supplied by this company.
+Each statement is written down explicitly, in a form both people and software can follow.
+
+The three identifiers do not disappear.
+They become properties of one product, so any fact can be traced back to the system it came from, and written back to it where that makes sense.
+
+The question from purchasing now has a place to be asked, and an answer that is the same for everyone who asks it.
+
+![Suppliers, the products they supply and the countries they are in, shown in Graph Insights. Every connection carries a name.](graph-insights-suppliers-products-countries.png){ class="bordered" width="60%" }
+
+Around the graph, the platform provides what is needed to keep it alive: building it from real sources, exploring and correcting it, checking that it still meets expectations, and serving it to the people and applications that need answers.
+
+- [What is a knowledge graph?](introduction/what-is-a-knowledge-graph/index.md) explains the idea in more depth.
+- [eccenca Corporate Memory at a glance](introduction/corporate-memory-at-a-glance/index.md) shows how the parts of the product fit together.
+
+### Terms used in this documentation
+
+These terms are not needed for this introduction.
+They become useful once reading continues into the other sections.
+
+| Term | In one line |
+| --- | --- |
+| Mapping | How source columns become things and relationships in the graph. |
+| Linking | Deciding when two records from different systems mean the same thing. |
+| Shapes (SHACL) | Writing down what must be true about the data, and checking it. |
+| Vocabulary | The agreed names for the kinds of things and relationships in use. |
+| Workflow | Running all of it again whenever the sources change. |
+| Marketplace | Ready-made packages to install and adapt. |
+| cmemc | Doing the same from the command line, for automation and CI/CD. |
+
+### What it is and what it is not
+
+| Corporate Memory is … | … and it is not |
+| --- | --- |
+| a layer that connects with existing systems | a replacement for them; the ERP system stays the ERP system |
+| built to represent meaning and relationships | a data warehouse or a BI tool for aggregating numbers |
+| configured for business users by people who know the data and the domain | a finished application for end users |
+| support for modeling decisions | a way to avoid them |
+
+It does not wire the systems to each other either.
+Corporate Memory connects with them, brings their data together in one graph, and leaves them running as they are.
+
+The last row matters most.
+Deciding what the data means is modeling work.
+Corporate Memory supports that work, it does not do it.
+
+### Is it the right tool?
+
+Corporate Memory is likely to add value when most of these questions are answered with yes:
+
+- Do the questions cross system boundaries?
+- Is the same real-world thing represented differently in different places?
+- Do relationships matter as much as the values themselves?
+- Is the structure of the data expected to keep changing?
+
+It is probably not the right tool for a single well-structured source with a stable schema, or for a question that is essentially "sum this column by month".
+It is also not the right tool when nobody in the organization is available to decide what the data means.
+That last one is the most common reason such projects stall, and no software solves it.
+
+### Who works with it
+
+<div class="grid cards" markdown>
+
+- __Linked Data Experts and data engineers__
+
+    ---
+
+    Do most of the building: connect sources, model, and keep the graph current.
+
+    [:octicons-arrow-right-24: Build a knowledge graph](build/index.md)
+
+- __Business users__
+
+    ---
+
+    Work with what has been configured for them, usually without seeing the model behind it.
+
+    [:octicons-arrow-right-24: Explore and manage knowledge](explore-and-author/index.md)
+
+- __Developers__
+
+    ---
+
+    Integrate Corporate Memory with other applications and extend it.
+
+    [:octicons-arrow-right-24: Extend Corporate Memory](develop/index.md)
+
+- __Administrators__
+
+    ---
+
+    Install, operate and upgrade it.
+
+    [:octicons-arrow-right-24: Deploy and operate](deploy-and-configure/index.md)
+
+</div>
+
+Choosing one of these roles is not required at this point.
+
+### Next
+
+- [What is a knowledge graph?](introduction/what-is-a-knowledge-graph/index.md): the concept, 5 minutes, on the main path
+- [Semantic Web basics](introduction/semantic-web-basics/index.md): optional, the terminology, about 35 minutes
+- [eccenca Corporate Memory at a glance](introduction/corporate-memory-at-a-glance/index.md): the parts of the product and how they relate

docs/index.md

@@ -0,0 +1,7 @@
+---
+nav:
+    - "What is a knowledge graph?": what-is-a-knowledge-graph
+    - Semantic Web basics: semantic-web-basics
+    - At a glance: corporate-memory-at-a-glance
+    - Get access: get-access
+    - See it in the product: see-it-in-the-product

docs/introduction/.pages

@@ -0,0 +1,89 @@
+---
+title: "Introduction: eccenca Corporate Memory at a glance"
+---
+
+# eccenca Corporate Memory at a glance
+
+[What is a knowledge graph?](../what-is-a-knowledge-graph/index.md) explains the knowledge graph in the middle of the following picture.
+The five areas around it are where the work with that graph happens.
+Each area is a part of eccenca Corporate Memory, and each has its own section in this documentation.
+The following descriptions say what each one is for, in two or three sentences, and nothing about how to use it.
+
+![Overview of Corporate Memory: the knowledge graph in the center, connected to Build, Explore and Consume, with Govern and Distribute across all three](corporate-memory-overview.png){ width="80%" }
+
+## Build
+
+Build is where data becomes a knowledge graph.
+A source is connected: a file, a database, an API.
+Its columns are then defined as things and relationships, and the Mapping Creator proposes most of that.
+Workflows put the steps in order, so the graph can be rebuilt whenever the sources change.
+
+Mostly used by Linked Data Experts and data engineers.
+
+[:octicons-arrow-right-24: Go to Build](../../build/index.md)
+
+## Explore
+
+Explore is where people work with the graph.
+Searching finds a thing, its connections become visible, and what is wrong is corrected in place, without a query language.
+Views can be tailored to a task, so a colleague sees their own fields rather than the model behind them.
+
+Used by business users and Linked Data Experts.
+
+[:octicons-arrow-right-24: Go to Explore](../../explore-and-author/index.md)
+
+## Consume
+
+Consume is where other systems take over.
+Dashboards, applications, automated processes and AI agents read the same graph through standard interfaces such as SPARQL, SQL and REST.
+Everyone then works from the same answer instead of a copy of their own.
+
+Used by developers, analysts and Linked Data Experts.
+
+[:octicons-arrow-right-24: Go to Consume](../../consume/index.md)
+
+## Govern
+
+Govern is what keeps the whole thing dependable.
+Access rules decide who sees and changes what, and metrics and logs show whether the system is healthy.
+Everything that can be done by hand can also be done from the command line or through an API.
+That is what makes automation and continuous delivery possible.
+
+Used by administrators and operations teams.
+
+[:octicons-arrow-right-24: Go to Automate](../../automate/index.md) · [:octicons-arrow-right-24: Go to Deploy and Configure](../../deploy-and-configure/index.md)
+
+## Distribute
+
+Distribute is how work gets reused.
+The Marketplace holds ready-made content that can be added to an instance: vocabularies, taxonomies, data graphs, Build projects and query catalogs.
+Complete demo and solution setups are included.
+Everything arrives as a versioned package, and Corporate Memory puts its contents where they belong.
+Solutions built in house can be packaged and shared the same way.
+
+Used by Linked Data Experts and developers.
+
+[:octicons-arrow-right-24: Go to Distribution](../../distribution/index.md)
+
+## What else it can do
+
+The five areas above are where most work happens.
+The following capabilities exist alongside them, and are named here so that they are known to exist rather than explained.
+
+| Capability | In one line | Where |
+| --- | --- | --- |
+| Query and SPARQL | The query language for graphs, and the precise way to ask the data a question nobody planned for. | [Queries](../../explore-and-author/query-module/index.md) |
+| Reasoning | Derives the facts that follow from the data and the rules, without anyone stating them. | [Reason](../../build/reference/customtask/cmem_plugin_reason-plugin_reason-ReasonPlugin.md) |
+| Shapes (SHACL) | Record what must be true about the data, and check whether it is. | [Building a customized user interface](../../explore-and-author/graph-exploration/building-a-customized-user-interface/index.md) |
+| Linking rules | Decide when two records from different systems mean the same real-world thing. | [Link Rules](../../explore-and-author/link-rules/index.md) |
+| Link learning | Proposes those rules from examples, instead of requiring them to be written by hand. | [Active Learning](../../build/active-learning/index.md) |
+| Python plugins | Add functions that the standard product does not provide. | [Python Plugins](../../develop/python-plugins/index.md) |
+| Deployment | The technical operating layer, so Corporate Memory runs in different environments. | [Deploy and Configure](../../deploy-and-configure/index.md) |
+
+## Next
+
+- [Get access](../get-access/index.md): a sandbox or an existing instance
+- Basic, the hands-on path to a first knowledge graph in about four hours, is in preparation.
+  Until then, the [Tutorials](../../tutorials/index.md) cover the first steps.
+
+<!-- TODO: replace the Basic entry above with a link once the Basic learning path exists. -->