Thin front-end: mmrl_osc's BLE/VQF/OSC/tare/reconnect run unchanged on a
background asyncio thread; rumps owns the main thread and a ~5 Hz timer refreshes
the menu (live status/battery, yaw/pitch/roll, board temp) with items to tare,
switch BSX/VQF, toggle CSV logging, rescan, and quit. mmrl_osc gains small
non-breaking hooks: conn_status/battery_pct globals, find_metawear() for
non-interactive scan, and run() tolerates not being on the main thread. CLI is
unchanged. README documents the GUI; rumps added to requirements as optional.