- Change 'already_running' to 'already_scanning' status in bluetooth_v2
so frontend recognizes the response and connects the SSE stream
- Hide pagerScopePanel and sensorScopePanel in switchMode() to prevent
audio waveform bars leaking into other modes
- Clear devices Map, pendingDeviceIds Set, and UI in BluetoothMode.destroy()
to prevent memory accumulation on repeated mode switches
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>