Releep scale SDK compatibility fork

Vendored from releep_scale_connect 1.0.1 (see LICENSE). Dart and iOS interfaces are retained. Android changes:

  • Accept the base Android Activity, including FlutterFragmentActivity, instead of casting the host to FlutterActivity during registration.
  • Request permissions and Bluetooth activation through the app's scan flow, rather than during plugin registration.
  • Release the previous discovery callback when a new listener starts; stop discovery and remove pending timers when a listener cancels.
  • Report Bluetooth, permission, SDK initialization and scan-start errors through the discovery EventChannel.

The application uses this path dependency so fixes survive SDK cache refreshes and CI builds. Native changes require a full Android rebuild.