ESP32 Car

Reworked Android controller for an ESP32-CAM 2WD RC car.

What changed The transport is identified correctly as Classic Bluetooth SPP, not BLE. New RcViewModel owns Bluetooth/Wi-Fi control state and tuning. New Drive screen combines transport selection, hold-to-drive D-pad, speed, trim, light, and emergency stop. New Device screen handles paired-device connection, reconnect, Wi-Fi provisioning, IP/status, and protocol visibility. Existing camera controller and OpenCV auto-tracking features are retained. Runtime "C++ code" screen was removed; firmware now lives in /firmware where it belongs. Bluetooth writes are serialized; link errors and last-device reconnect state are exposed. Wi-Fi drive requests cancel stale drive calls to reduce command backlog. Android permission surface was reduced to what this SPP + LAN app actually needs. Firebase/Room/Secrets/AI Studio build baggage and dozens of patch scripts were removed. Firmware v3.0 fixes the old reboot behavior that alternated BT/Wi-Fi modes on every boot.