Add stop-all buttons to target sections, perf chart color reset, and TODO

- Add stop-all buttons to LED targets and KC targets section headers
  (visible only when targets are running, uses headerExtra on CardSection)
- Add reset ability to performance chart color pickers (removes custom
  color from localStorage and reverts to default)
- Remove CODEBASE_REVIEW.md
- Add prioritized TODO.md with P1/P2/P3 feature roadmap

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

TODO.md

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+# Pending Features & Issues
+
+Priority: `P1` quick win · `P2` moderate · `P3` large effort
+
+## Processing Pipeline
+
+- [ ] `P1` **Noise gate** — Suppress small color changes below threshold, preventing shimmer on static content
+- [ ] `P1` **Color temperature filter** — Warm/cool shift separate from hue shift (circadian/mood)
+- [ ] `P1` **Zone grouping** — Merge adjacent LEDs into logical groups sharing one averaged color
+- [ ] `P2` **Palette quantization** — Force output to match a user-defined palette
+- [ ] `P2` **Drag-and-drop filter ordering** — Reorder postprocessing filter chains visually
+- [ ] `P3` **Transition effects** — Crossfade, wipe, or dissolve between sources/profiles instead of instant cut
+
+## Output Targets
+
+- [ ] `P1` **Rename `picture-targets` to `output-targets`** — Rename API endpoints and internal references for clarity
+- [ ] `P2` **OpenRGB** — Control PC peripherals (keyboard, mouse, RAM, fans) as ambient targets
+- [ ] `P2` **Art-Net / sACN (E1.31)** — Stage/theatrical lighting protocols, DMX controllers
+
+## Automation & Integration
+
+- [ ] `P2` **Webhook/MQTT trigger** — Let external systems activate profiles without HA integration
+- [ ] `P2` **WebSocket event bus** — Broadcast all state changes over a single WS channel
+- [ ] `P3` **Notification reactive** — Flash/pulse on OS notifications (optional app filter)
+
+## Multi-Display
+
+- [ ] `P2` **Investigate multimonitor support** — Research and plan support for multi-monitor setups
+- [ ] `P3` **Multi-display unification** — Treat 2-3 monitors as single virtual display for seamless ambilight
+
+## Capture Engines
+
+- [ ] `P3` **SCRCPY capture engine** — Implement SCRCPY-based screen capture for Android devices
+- [ ] `P3` **Camera / webcam** — Border-sampling from camera feed for video calls or room-reactive lighting
+
+## UX
+
+- [ ] `P3` **PWA / mobile layout** — Mobile-first layout + "Add to Home Screen" manifest