Add the NestQuest logo to the README and prepare brands icons (task ac84fa96)

Embed the transparent logo at the top of README.md so it shows on the HACS
repository page (render_readme). Generate icon/logo PNGs at 256 and 512 for
a home-assistant/brands pull request at custom_integrations/nestquest/,
with an offline, deterministic generator and a note on how they are used.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

design/logos/brands/custom_integrations/nestquest/README.md

@@ -0,0 +1,31 @@
+# Home Assistant brands files for NestQuest
+
+These files are prepared for a pull request to
+[`github.com/home-assistant/brands`](https://github.com/home-assistant/brands),
+placed at `custom_integrations/nestquest/`:
+
+| File | Size |
+|------|------|
+| `icon.png` | 256×256 |
+| `icon@2x.png` | 512×512 |
+| `logo.png` | 256×256 |
+| `logo@2x.png` | 512×512 |
+
+Home Assistant and HACS load integration icons from `brands.home-assistant.io`,
+which is built from that repository. Once the pull request is merged, the
+NestQuest icon shows on the HACS card and on the Home Assistant integrations
+page. Nothing in this repository can change that icon directly.
+
+The alternative (HACS only) is to set the avatar of the GitHub
+`Maniacs-Mansion` organization to the NestQuest logo; HACS falls back to the
+repository owner's avatar when no brands icon exists.
+
+## Regenerating
+
+The PNGs are generated offline and deterministically (pure Node, zlib only)
+from `design/logos/NestQuest-NoBG.png`, box-filter downscaled with
+transparency kept. From the repository root:
+
+```bash
+node design/logos/brands/generate-brand-icons.mjs
+```