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>

server/src/wled_controller/static/locales/en.json

@@ -1093,6 +1093,9 @@
   "target.error.clone_failed": "Failed to clone target",
   "target.error.autostart_toggle_failed": "Failed to toggle auto-start",
   "target.error.delete_failed": "Failed to delete target",
+  "targets.stop_all.none_running": "No targets are currently running",
+  "targets.stop_all.stopped": "Stopped {count} target(s)",
+  "targets.stop_all.error": "Failed to stop targets",
   "audio_source.error.load": "Failed to load audio source",
   "audio_template.error.clone_failed": "Failed to clone audio template",
   "value_source.error.load": "Failed to load value source",