docs: refactor README into separate documentation files

split the project documentation into focused markdown files for easier navigation and maintenance

- keep the main README focused on usage and command reference
- move development and contribution guidelines to CONTRIBUTING.md
- move packaging and release instructions to PACKAGING.md
- add links between the documentation files
- add a table of contents to the README

Author: nos1dot618

CONTRIBUTING.md

@@ -0,0 +1,51 @@
+# Contributing
+
+Thanks for contributing to Java Inventory.
+
+## Development setup
+
+Install the required tools listed in the [README](README.md#requirements), then initialize the project:
+
+```shell
+python java_inventory.py setup
+```
+
+Use the CLI directly while developing:
+
+```shell
+python java_inventory.py --help
+```
+
+## Before submitting changes
+
+Run the linter against your staged changes:
+
+```shell
+python java_inventory.py lint . --cached
+```
+
+For changes to inventory or coverage behavior, also run the relevant command against the development test project.
+
+For example:
+
+```shell
+python java_inventory.py test-coverage \
+    dev-test/src/main \
+    dev-test/src/test
+```
+
+If packaging code changes, verify a local build:
+
+```shell
+python build.py
+```
+
+## Pull requests
+
+Keep changes focused and describe:
+
+- what changed;
+- why it changed;
+- how it was tested.
+
+Include generated reports or build artifacts only when they are specifically useful for reviewing the change.

PACKAGING.md

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+# Packaging
+
+`java-inventory` can be packaged as a standalone executable with PyInstaller.
+
+## Local build
+
+```shell
+python package.py
+```
+
+The build:
+
+1. Creates `.venv` when needed.
+2. Installs PyInstaller in the build environment.
+3. Runs `python java_inventory.py setup`.
+4. Verifies the required Java artifacts.
+5. Packages the application and resources.
+
+Output:
+
+```shell
+dist/java-inventory
+```
+
+On Windows:
+
+```powershell
+dist\java-inventory.exe
+```
+
+Run the packaged binary with:
+
+```shell
+./dist/java-inventory --help
+```
+
+Windows:
+
+```powershell
+dist\java-inventory.exe --help
+```
+
+## Options
+
+Skip cleanup:
+
+```shell
+python package.py --no-cleanup
+```
+
+Use another PyInstaller spec:
+
+```shell
+python package.py --spec path/to/custom.spec
+```
+
+Enable debug output:
+
+```shell
+python package.py --debug
+```
+
+## Platform builds
+
+PyInstaller produces a native executable for the platform where it runs. Build separately on each target platform.
+
+Official releases use GitHub Actions to build platform-specific binaries and attach them to GitHub Releases.
+
+The packaging environment requires Python, a JDK, and Maven because `setup` builds the Java components used by the application.