Fix: Implement Google Cast functionality by implementing CastMediaRouteController methods [FaaFyfxR9WAQrL7FcAgEHJvztd8cVMxvjHRS55rw1nwH]

[waterWang]

Summary

This PR fixes Google Cast (Chromecast) functionality in microG by implementing the previously stubbed CastMediaRouteController methods. The cast button has been showing discovered devices, but selecting a device did nothing because onSelect(), onControlRequest(), onRelease(), and other methods were empty stubs.

Changes

CastMediaRouteController.java - All methods implemented:

• onSelect(): Connects to the Chromecast device via TCP/TLS using the existing su.litvak.chromecast.api.v2 library
• onControlRequest(): Handles all media control intents (play, pause, seek, stop, volume, session management)
• onRelease(): Properly disconnects from the device
• onSetVolume() / onUpdateVolume(): Controls Chromecast volume
• onUnselect(): Disconnects from the device when user deselects it

Related

Fixes #580

Verification

• Implements the same API surface as the existing stub, matching Android's MediaRouteProvider.RouteController interface
• Uses the existing su.litvak.chromecast.api.v2 library already included in the project
• All async operations use AsyncTask (matching the project's existing patterns)

Checklist

• Code compiles and builds
• All stubs are now properly implemented
• Uses only existing project dependencies