…round, with notification controls for managing the call

- Add CallForegroundService with persistent notification
- Support calls in background without requiring picture-in-picture mode
- Add "Return to call" and "End call" action buttons to CallForegroundService notification with corresponding PendingIntent
- Handle proper foreground service types for microphone/camera permissions
- Add notification permission and fallback messaging.
- Add EndCallReceiver to handle end call broadcasts from notification action
- Use existing ic_baseline_close_24 drawable for end call action icon
- Register broadcast receiver in CallActivity to handle end call requests from notification using ReceiverFlag.NotExported for Android 14+ compatibility
- Add proper cleanup flow: notification action → EndCallReceiver → CallActivity → proper hangup sequence
- Track intentional call leaving to prevent unwanted service restarts
- Release proximity sensor lock properly during notification-triggered hangup
- Add diagnostic logging throughout the end call flow for debugging

Signed-off-by: Tarek Loubani <tarek@tarek.org>

- refactoring
- linter

Signed-off-by: rapterjet2004 <juliuslinus1@gmail.com>

Signed-off-by: rapterjet2004 <juliuslinus1@gmail.com>