- Add FPS control (1-60, default 20) to test preview modal next to LED count - Server accepts fps query param, controls frame send interval - Single Apply icon button (✓) applies both LED count and FPS - FPS control stays visible for picture sources (LED count hidden) - Fix composite sub-stream consumer ID collision: use unique instance ID to prevent old WebSocket release from killing new connection's streams Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>