- Replace stored phone_config.txt with _get_wireless_serial() which
parses 'adb devices' and auto-picks the ip:port (wireless) entry
- Replace _scan_phone_port-based reconnect with _try_wireless_reconnect
that scans local /24 subnet on port 5555 via parallel probing
- Add _get_local_subnet_prefix() using UDP socket trick (8.8.8.8:80)
- Remove PHONE_CONFIG_FILE, _load_phone_config, _save_phone_config,
_save_connected_device_config, _scan_phone_port
- No config file needed; device is always discovered dynamically
- 112 tests passing