fix(ios): activate AVAudioSession before connect to fix voice

Root cause: OSStatus 561145187 - AVAudioSession was not in
.playAndRecord + .voiceChat mode when VoiceProcessingIO tried to start.

Two changes:
1. Activate session BEFORE rust.connect() so it is ready when auto-join runs
2. Defensive activation in Connected handler as backup (idempotent)

This fixes both the audio error and the subsequent voice_in already taken
error that occurred after auto-join consumed voice_in on failure.

apps/chanora_flutter/lib/main.dart

@@ -748,6 +748,7 @@ class _BetaHomeState extends State<_BetaHome> with WidgetsBindingObserver {
           _reconnectAttempt = null;
           _reconnectDelay = null;
         });
+        unawaited(iosAudioSessionController.activate());
         unawaited(_refreshSnapshot(recordActivity: false, reportErrors: true));
       case rust.BridgeEvent_Lost(:final reason):
         _recordUiDiagnostic('connection', 'lost: $reason');
@@ -1161,6 +1162,7 @@ class _BetaHomeState extends State<_BetaHome> with WidgetsBindingObserver {
       _chatMessages.clear();
     });
     _releaseFocusedPttIfHeld();
+    await iosAudioSessionController.activate();
     try {
       final snap = await rust.connect(
         host: (host ?? _hostCtl.text).trim(),