Future Enhancements - Cast Button & Media Routing

[tobexyz]

YaaccMediaRouteProvider is implemented but not exposed in the UI. Adding Cast button would provide standard Android device selection.

1. Standard Android UI - Users familiar with Cast button
2. Unified device selection - All devices in one place
3. System volume routing - Android handles volume automatically
4. Modern UX - Consistent with other media apps

but need a refactoring of ux/ui