Add on-device logger

src/screens/PreviewScreen.tsx

@@ -23,6 +23,7 @@ import {
 import { THEME } from '../styles/theme';
 import { printImageLocal } from '../services/printer';
 import { saveToGallery } from '../services/storage';
+import { logger } from '../services/logger';
 import DraggableSticker, { StickerData } from '../components/DraggableSticker';
 import StickerTray from '../components/StickerTray';
 import FrameOverlay from '../components/FrameOverlay';
@@ -70,6 +71,13 @@ export default function PreviewScreen({
   const [selectedStickerId, setSelectedStickerId] = useState<string | null>(null);
   const [showStickerTray, setShowStickerTray] = useState<boolean>(false);
 
+  React.useEffect(() => {
+    logger.log(`PreviewScreen mounted with ${photoUris.length} photos. currentPhoto: ${photoUris[photoUris.length - 1]}`);
+    return () => {
+      logger.log('PreviewScreen unmounting.');
+    };
+  }, [photoUris]);
+
   // Idle Timer state
   const idleTimerRef = useRef<any>(null);