Add screenshot content analysis using VLM

Features:
- ScreenshotAnalyzer class for VLM-based image analysis
- Real-time analysis during video recording
- Extract likes, comments, tags, category from screenshots
- Frontend display for category badges and tags
- Batch analysis API endpoint

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

.gitignore

@@ -65,4 +65,7 @@ call_model.py
 app_package_name.py
 
 .claude/
-.venv
+.venv
+
+# Video learning data
+video_learning_data/