Add a brand icon

Since HA 2026.x the brands component serves
/api/brands/integration/<domain>/<image> from a custom integration's own
brand/ directory before falling back to the brands CDN, so without one the
integration renders as the grey placeholder. Add brand/icon.png (256x256) and
brand/icon@2x.png (512x512) - a mesh lattice, drawn by
make_brand_icons.py in the applications repo.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

README.md

@@ -251,5 +251,16 @@ action:
 - Assist replies use the standard conversation pipeline, so whichever agent you
   select (built-in intents, a local LLM, a cloud LLM, …) is what answers.
 
+## Brand icon
+
+`custom_components/reticulum/brand/icon.png` (256x256) and `icon@2x.png`
+(512x512) are the integration's own icon. Since HA 2026.x the `brands`
+component serves `/api/brands/integration/reticulum/<image>` from a custom
+integration's `brand/` directory before falling back to the brands CDN, so
+without them the integration shows the grey placeholder. Detection is
+`Integration.has_branding`, which only checks that a top-level `brand`
+directory exists - it is a cached property, so Home Assistant has to be
+restarted after the files land.
+
 ## License
 MIT