fix(android): disable AudioSwitch audio focus to fix stuck volume controls after call

Telecom (callkeep) already manages audio focus for self-managed VoIP
calls. AudioSwitch holding a concurrent permanent AUDIOFOCUS_GAIN kept
Android in call audio mode after the call ended on older MIUI devices,
causing volume buttons to control call volume instead of media volume.

Disabling manageAudioFocus prevents AudioSwitch from requesting focus
while leaving device routing (earpiece/speaker/bluetooth) intact.

Fixes WT-1429

Author: SERDUN

lib/features/call/utils/call_media_manager.dart

@@ -47,7 +47,11 @@ class CallMediaManager {
   void _configure() {
     if (Platform.isAndroid) {
       AndroidNativeAudioManagement.setAndroidAudioConfiguration(
-        AndroidAudioConfiguration(preferredOutputOrder: _voiceCallOutputOrder),
+        AndroidAudioConfiguration(
+          preferredOutputOrder: _voiceCallOutputOrder,
+          // Telecom owns audio focus; dual ownership leaves volume stuck in call mode on older MIUI (WT-1429).
+          manageAudioFocus: false,
+        ),
       );
     }
     if (Platform.isIOS) AppleNativeAudioManagement.setUseManualAudio(true);