fix(mobile): increase message bar padding above keyboard

Add extra padding (keyboardHeight + 10) so the input comfortably
clears the keyboard suggestions/accessory bar on all devices.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/mobile/src/screens/SessionDetailScreen.tsx

@@ -350,7 +350,7 @@ export default function SessionDetailScreen({ route, navigation }: Props) {
 
       {/* Message input — only show for active sessions */}
       {!isDone && (
-        <View style={[styles.messageBar, { paddingBottom: keyboardHeight > 0 ? keyboardHeight - (Platform.OS === "ios" ? 34 : 0) : 10 }]}>
+        <View style={[styles.messageBar, { paddingBottom: keyboardHeight > 0 ? keyboardHeight + 10 : 10 }]}>
           <TextInput
             style={styles.messageInput}
             placeholder="Send message to agent..."