Add audio output switcher for voice calls (Android speaker fix)

- Add Audio button during active calls to switch output
- Fallback to Speaker/Earpiece options when LiveKit API unavailable
- Speaker now works correctly on Android

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/(tabs)/chat.tsx

@@ -45,6 +45,7 @@ import {
 import { ConnectionState, Track } from 'livekit-client';
 import { getToken, type BeneficiaryData } from '@/services/livekitService';
 import { useAuth } from '@/contexts/AuthContext';
+import { getAvailableAudioOutputs, selectAudioOutput, setAudioOutput } from '@/utils/audioSession';
 
 // Register LiveKit globals (must be called before using LiveKit)
 registerGlobals();
@@ -612,6 +613,40 @@ export default function ChatScreen() {
     endVoiceCallContext();
   }, [endVoiceCallContext, callState.callDuration]);
 
+  // Audio output picker
+  const showAudioPicker = useCallback(async () => {
+    const devices = await getAvailableAudioOutputs();
+
+    // If devices found from LiveKit API, use them
+    if (devices.length > 0) {
+      const buttons: any[] = devices.map(device => ({
+        text: device.name,
+        onPress: () => selectAudioOutput(device.id),
+      }));
+      buttons.push({ text: 'Cancel', style: 'cancel' });
+      Alert.alert('Audio Output', 'Select audio device:', buttons);
+      return;
+    }
+
+    // Fallback for Android (and iOS if no devices found)
+    // Show simple Speaker/Earpiece toggle using setAudioOutput()
+    Alert.alert(
+      'Audio Output',
+      'Select audio output:',
+      [
+        {
+          text: '🔊 Speaker',
+          onPress: () => setAudioOutput(true),
+        },
+        {
+          text: '📱 Earpiece',
+          onPress: () => setAudioOutput(false),
+        },
+        { text: 'Cancel', style: 'cancel' },
+      ]
+    );
+  }, []);
+
   // Handle voice transcript entries - add to chat in real-time
   const handleVoiceTranscript = useCallback((role: 'user' | 'assistant', text: string) => {
     if (!text.trim()) return;
@@ -1025,6 +1060,15 @@ export default function ChatScreen() {
               </Text>
             </View>
           )}
+          {/* Audio output button - only during active call */}
+          {isCallActive && (
+            <TouchableOpacity
+              style={styles.audioButton}
+              onPress={showAudioPicker}
+            >
+              <Ionicons name="volume-high" size={20} color={AppColors.primary} />
+            </TouchableOpacity>
+          )}
 
           <TextInput
             style={styles.input}
@@ -1238,6 +1282,17 @@ const styles = StyleSheet.create({
     backgroundColor: AppColors.error,
     borderColor: AppColors.error,
   },
+  audioButton: {
+    width: 44,
+    height: 44,
+    borderRadius: 22,
+    backgroundColor: AppColors.surface,
+    justifyContent: 'center',
+    alignItems: 'center',
+    marginRight: Spacing.sm,
+    borderWidth: 1,
+    borderColor: AppColors.primary,
+  },
   callActiveIndicator: {
     width: '100%',
     height: '100%',