fix: harden call cleanup to guarantee nothing is left running

Three issues addressed:

1. Make cleanup() exception-safe: wrap each WebRTC dispose call in
   its own try-catch so that a failure in one (e.g. native crash
   disposing a PeerConnection) does not skip releasing the camera,
   audio mode, foreground service, or EGL context.

2. Upgrade the Idle safety net to call cleanup() instead of only
   stopping ringing/notifications. If the Ended state is missed due
   to StateFlow conflation, the Idle handler now performs full
   resource cleanup (camera, WebRTC, audio mode, foreground service,
   proximity wake lock). cleanup() is idempotent since all resources
   are null-checked and nulled out.

3. Call cleanup() in AccountViewModel.onCleared() so that WebRTC
   resources, camera, audio mode, and foreground service are released
   when the ViewModel is destroyed (e.g. logout, activity recreation).

4. Clear processedEventIds when transitioning to Idle to prevent
   unbounded memory growth across calls.

https://claude.ai/code/session_01GWRdrVAa29BsDkv8R7Z3Y9

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/call/CallManager.kt

@@ -606,6 +606,7 @@ class CallManager(
                 delay(ENDED_DISPLAY_MS)
                 if (_state.value is CallState.Ended) {
                     _state.value = CallState.Idle
+                    processedEventIds.clear()
                 }
             }
     }