Add Chat tab with Julia AI + voice call improvements

- Enable Chat tab (replace Debug) - text chat with Julia AI
- Add voice call button in chat header and input area
- Add speaker/earpiece toggle in voice-call screen
- setAudioOutput() function for switching audio output

app/(tabs)/_layout.tsx

@@ -46,11 +46,14 @@ export default function TabLayout() {
           href: null,
         }}
       />
-      {/* Chat hidden for now - testing via debug */}
+      {/* Chat with Julia AI */}
       <Tabs.Screen
         name="chat"
         options={{
-          href: null,
+          title: 'Julia',
+          tabBarIcon: ({ color, size }) => (
+            <Feather name="message-circle" size={22} color={color} />
+          ),
         }}
       />
       {/* Voice tab hidden - using Debug for testing */}
@@ -69,14 +72,11 @@ export default function TabLayout() {
           ),
         }}
       />
-      {/* Debug tab for testing */}
+      {/* Debug tab hidden */}
       <Tabs.Screen
         name="debug"
         options={{
-          title: 'Debug',
-          tabBarIcon: ({ color, size }) => (
-            <Feather name="code" size={22} color={color} />
-          ),
+          href: null,
         }}
       />
       {/* Hide explore tab */}

app/voice-call.tsx

@@ -35,6 +35,7 @@ import { AppColors, BorderRadius, FontSizes, Spacing } from '@/constants/theme';
 import { VOICE_NAME } from '@/services/livekitService';
 import { useVoiceTranscript } from '@/contexts/VoiceTranscriptContext';
 import { useLiveKitRoom, ConnectionState } from '@/hooks/useLiveKitRoom';
+import { setAudioOutput } from '@/utils/audioSession';
 
 const { width: SCREEN_WIDTH } = Dimensions.get('window');
 
@@ -47,6 +48,9 @@ export default function VoiceCallScreen() {
   const [logsMinimized, setLogsMinimized] = React.useState(false);
   const logsScrollRef = useRef<ScrollView>(null);
 
+  // Speaker/earpiece toggle state
+  const [isSpeakerOn, setIsSpeakerOn] = React.useState(true);
+
   // LiveKit hook - ALL logic is here
   const {
     state,
@@ -159,6 +163,13 @@ export default function VoiceCallScreen() {
     router.back();
   };
 
+  // Toggle speaker/earpiece
+  const handleToggleSpeaker = async () => {
+    const newSpeakerState = !isSpeakerOn;
+    setIsSpeakerOn(newSpeakerState);
+    await setAudioOutput(newSpeakerState);
+  };
+
   // Copy logs to clipboard
   const copyLogs = async () => {
     const logsText = logs.map(l => `[${l.timestamp}] ${l.message}`).join('\n');
@@ -376,10 +387,18 @@ export default function VoiceCallScreen() {
           <Ionicons name="call" size={32} color={AppColors.white} />
         </TouchableOpacity>
 
-        {/* Speaker button (placeholder for future) */}
-        <TouchableOpacity style={styles.controlButton} disabled>
-          <Ionicons name="volume-high" size={28} color={AppColors.white} />
-          <Text style={styles.controlLabel}>Speaker</Text>
+        {/* Speaker/Earpiece toggle */}
+        <TouchableOpacity
+          style={[styles.controlButton, isSpeakerOn && styles.controlButtonActive]}
+          onPress={handleToggleSpeaker}
+          disabled={!isActive}
+        >
+          <Ionicons
+            name={isSpeakerOn ? 'volume-high' : 'ear'}
+            size={28}
+            color={isSpeakerOn ? AppColors.success : AppColors.white}
+          />
+          <Text style={styles.controlLabel}>{isSpeakerOn ? 'Speaker' : 'Earpiece'}</Text>
         </TouchableOpacity>
       </View>
     </SafeAreaView>

utils/audioSession.ts

@@ -145,3 +145,45 @@ export async function reconfigureAudioForPlayback(): Promise<void> {
     // Don't throw - this is a best-effort operation
   }
 }
+
+/**
+ * Switch audio output between speaker and earpiece
+ *
+ * @param useSpeaker - true for speaker, false for earpiece
+ */
+export async function setAudioOutput(useSpeaker: boolean): Promise<void> {
+  if (Platform.OS !== 'ios') {
+    console.log('[AudioSession] setAudioOutput - skipping on non-iOS');
+    return;
+  }
+
+  console.log(`[AudioSession] Setting audio output to ${useSpeaker ? 'SPEAKER' : 'EARPIECE'}...`);
+
+  try {
+    const AudioSession = await getAudioSession();
+    if (!AudioSession) {
+      console.error('[AudioSession] Failed to get AudioSession module');
+      return;
+    }
+
+    // Configure audio output
+    await AudioSession.configureAudio({
+      ios: {
+        defaultOutput: useSpeaker ? 'speaker' : 'earpiece',
+      },
+    });
+
+    // Also update the full configuration to ensure it takes effect
+    await AudioSession.setAppleAudioConfiguration({
+      audioCategory: 'playAndRecord',
+      audioCategoryOptions: useSpeaker
+        ? ['allowBluetooth', 'allowBluetoothA2DP', 'defaultToSpeaker', 'mixWithOthers']
+        : ['allowBluetooth', 'allowBluetoothA2DP', 'mixWithOthers'],
+      audioMode: 'voiceChat',
+    });
+
+    console.log(`[AudioSession] Audio output set to ${useSpeaker ? 'SPEAKER' : 'EARPIECE'}`);
+  } catch (error) {
+    console.error('[AudioSession] setAudioOutput error:', error);
+  }
+}