Ship the NestQuest brand images in the integration's brand directory (task ac84fa96)

Home Assistant 2026.3+ serves custom_components/<domain>/brand/ ahead of the
brands CDN, so generate icon/logo PNGs (256 and 512, RGBA) into
custom_components/nestquest/brand/, which HACS installs with the integration.
Move the generator to design/logos/, add a --check mode, and drop the
obsolete brands-repository staging folder. Add tests that the four images
exist with the right size and reproduce byte-identically. Rewrite the note
to describe the local brand directory and the unverified HACS store card
caveat.

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

tests/test_brand_icons.py

@@ -0,0 +1,55 @@
+"""The integration's local brand images (Home Assistant 2026.3+).
+
+``custom_components/nestquest/brand/`` ships through HACS with the
+integration, and Home Assistant serves those images ahead of the brands CDN.
+They are generated offline from ``design/logos/NestQuest-NoBG.png`` by
+``design/logos/generate-brand-icons.mjs``; these checks fail if the directory
+goes missing, changes shape, or drifts from a fresh generation.
+"""
+from __future__ import annotations
+
+import shutil
+import struct
+import subprocess
+from pathlib import Path
+
+import pytest
+
+REPO_ROOT = Path(__file__).parent.parent
+BRAND_DIR = REPO_ROOT / "custom_components" / "nestquest" / "brand"
+GENERATOR = REPO_ROOT / "design" / "logos" / "generate-brand-icons.mjs"
+EXPECTED = {
+    "icon.png": 256,
+    "icon@2x.png": 512,
+    "logo.png": 256,
+    "logo@2x.png": 512,
+}
+PNG_SIGNATURE = b"\x89PNG\r\n\x1a\n"
+
+
+def test_brand_dir_holds_exactly_the_four_images() -> None:
+    assert sorted(p.name for p in BRAND_DIR.iterdir()) == sorted(EXPECTED)
+
+
+@pytest.mark.parametrize(("name", "size"), sorted(EXPECTED.items()))
+def test_brand_image_is_square_rgba_png(name: str, size: int) -> None:
+    data = (BRAND_DIR / name).read_bytes()
+    assert data[:8] == PNG_SIGNATURE
+    assert data[12:16] == b"IHDR"
+    width, height, depth, colour = struct.unpack(">IIBB", data[16:26])
+    assert (width, height) == (size, size)
+    assert (depth, colour) == (8, 6)  # 8-bit RGBA keeps the transparency
+
+
+def test_generator_reproduces_the_committed_images() -> None:
+    node = shutil.which("node")
+    if node is None:
+        pytest.skip("needs node")
+    result = subprocess.run(
+        [node, str(GENERATOR), "--check"],
+        cwd=REPO_ROOT,
+        capture_output=True,
+        text=True,
+        check=False,
+    )
+    assert result.returncode == 0, result.stderr