docs: add placeholder mark and home-assistant/brands instructions

HA/HACS icons come from home-assistant/brands, not this repo. Add an
original placeholder SVG, a README banner, and branding/ with the exact
icon specs, PR steps and a note on the CHINT trademark.

Author: Developer089

README.md

@@ -1,3 +1,7 @@
+<p align="center">
+  <img src="branding/dtsu666_meter.svg" alt="DTSU666 Meter" width="120" height="120">
+</p>
+
 # DTSU666 Energy Meter — Home Assistant integration (Modbus TCP)
 
 Home Assistant integration that reads a **CHINT DTSU666 / DTSU666-H** three-phase
@@ -94,6 +98,16 @@ logger:
     custom_components.dtsu666_meter: debug
 ```
 
+## Icon
+
+Home Assistant / HACS pull the integration icon from the central
+[`home-assistant/brands`](https://github.com/home-assistant/brands) repo, **not
+from this repository** — so a generic placeholder is shown until a brand is
+accepted there. See [`branding/README.md`](branding/README.md) for the exact
+image specs and the submission steps (and the note on using the CHINT
+trademark). The mark in this README is an original placeholder, not the CHINT
+logo.
+
 ## License
 
 MIT — see `LICENSE`.

branding/README.md

@@ -0,0 +1,49 @@
+# Branding / integration icon
+
+Home Assistant and HACS **do not read icons from this repository**. The icon
+shown for an integration comes from the central
+[`home-assistant/brands`](https://github.com/home-assistant/brands) repo. Until
+a brand is accepted there, HA shows a generic placeholder — that is expected.
+
+`dtsu666_meter.svg` here is an **original placeholder mark** (a neutral
+energy-meter motif), used only for this repo's README / GitHub social preview.
+It is intentionally **not** the CHINT corporate logo.
+
+## How to get a real icon into Home Assistant
+
+Submit a pull request to `home-assistant/brands`:
+
+```
+brands/
+  custom_integrations/
+    dtsu666_meter/
+      icon.png      # 256 x 256, square, transparent background, trimmed
+      logo.png      # optional, wider wordmark; transparent background
+      icon@2x.png   # optional 512 x 512 hDPI
+```
+
+Requirements (see `home-assistant/brands` CONTRIBUTING):
+
+- PNG, transparent background, content trimmed to the edges.
+- `icon.png` exactly 256×256 (square). `icon@2x.png` 512×512 if provided.
+- Optimised (e.g. `pngquant` / `oxipng`).
+- The domain folder name **must** match the integration domain:
+  `dtsu666_meter`.
+
+Steps:
+
+1. Fork `home-assistant/brands`, add the files above.
+2. `python3 -m script.hassfest` style checks run in CI there — keep sizes exact.
+3. Open the PR; the HA team reviews. Once merged, HA/HACS pick the icon up
+   automatically (no release needed on this side).
+
+## About the CHINT logo (trademark)
+
+The CHINT logo is CHINT's trademark. `home-assistant/brands` does accept
+manufacturer logos for device integrations (common practice), **but the image
+must be an officially sourced asset** — obtain it from CHINT brand resources or
+an authorised source. Do not trace/recreate it.
+
+This project cannot generate or reproduce that trademarked raster logo. Drop an
+officially sourced `icon.png` (256×256, transparent) into this folder and it can
+be wired into the brands PR.