feat(ui): release notes overlay v2 + settings/streams/dashboard polish

Release Notes overlay redesign (scoped via .release-notes-shell)
- Backend exposes release.assets (name/size/download_url) through
  UpdateReleaseInfo so the frontend can render real download links.
- New masthead: eyebrow + display-font title + tag/published/pre-release
  chip strip + close/external action buttons; opts out of layout.css's
  global `header { height: 60px }` and `header::before` accent bar that
  were leaking into the overlay's <header>.
- Markdown body: <code> filenames are wrapped in clickable <a> via fuzzy
  asset match (exact basename, then same-extension token-overlap), with
  per-asset description tooltip and a small download glyph.
- Per-asset description derived from filename pattern (Windows installer
  /portable/msi, Linux tarball/AppImage/deb/rpm, macOS dmg/pkg, Android
  apk/aab, iOS ipa, generic archives) with i18n keys in en/ru/zh.
- Hide checksum / signature side-files (.sha256/.sha512/.sig/.asc/...).

Settings modal & dashboard polish
- ds-section refresh, rail-channel routing, notif matrix updates.
- Dashboard customize panel + per-account layout updates.
- New docs/settings-modal-redesign.html design reference.

Streams / targets / color-strip
- Stream cards rewrite (cards.css, streams.css, streams.ts).
- Composite stream + metrics history adjustments.
- WLED target processor + color-strip pipeline refinements.
- Color-strip WS source streamer touch-ups.

Misc
- Perf charts overhaul; tabular game-integration / HA / MQTT / weather
  source cards; donation/sync-clocks/scene-presets minor polish.
- New i18n keys across en/ru/zh.

Test infrastructure
- conftest pre-creates the test DB so main.py's legacy-data migration
  doesn't shovel the user's production DB into the test temp dir.
- test_preferences_notifications wipes its own setting at the start of
  the defaults test (was relying on isolation it never enforced).

Pre-commit gates: ruff clean, tsc clean, npm run build clean,
pytest 899/899 passing.

CLAUDE.md

@@ -104,3 +104,42 @@ Do NOT commit code that fails linting or tests. Fix the issues first.
 - Follow existing code style and patterns
 - Update documentation when changing behavior
 - Never make commits or pushes without explicit user approval
+
+<!-- code-review-graph MCP tools -->
+## MCP Tools: code-review-graph
+
+**IMPORTANT: This project has a knowledge graph. ALWAYS use the
+code-review-graph MCP tools BEFORE using Grep/Glob/Read to explore
+the codebase.** The graph is faster, cheaper (fewer tokens), and gives
+you structural context (callers, dependents, test coverage) that file
+scanning cannot.
+
+### When to use graph tools FIRST
+
+- **Exploring code**: `semantic_search_nodes` or `query_graph` instead of Grep
+- **Understanding impact**: `get_impact_radius` instead of manually tracing imports
+- **Code review**: `detect_changes` + `get_review_context` instead of reading entire files
+- **Finding relationships**: `query_graph` with callers_of/callees_of/imports_of/tests_for
+- **Architecture questions**: `get_architecture_overview` + `list_communities`
+
+Fall back to Grep/Glob/Read **only** when the graph doesn't cover what you need.
+
+### Key Tools
+
+| Tool | Use when |
+|------|----------|
+| `detect_changes` | Reviewing code changes — gives risk-scored analysis |
+| `get_review_context` | Need source snippets for review — token-efficient |
+| `get_impact_radius` | Understanding blast radius of a change |
+| `get_affected_flows` | Finding which execution paths are impacted |
+| `query_graph` | Tracing callers, callees, imports, tests, dependencies |
+| `semantic_search_nodes` | Finding functions/classes by name or keyword |
+| `get_architecture_overview` | Understanding high-level codebase structure |
+| `refactor_tool` | Planning renames, finding dead code |
+
+### Workflow
+
+1. The graph auto-updates on file changes (via hooks).
+2. Use `detect_changes` for code review.
+3. Use `get_affected_flows` to understand impact.
+4. Use `query_graph` pattern="tests_for" to check coverage.