fix: improve AI tool reliability for face detection and background removal (#25)

- Replace OpenCV Haar Cascades with MediaPipe for face detection, using
  short-range model first with full-range fallback for better accuracy
- Add auto-orient to remove-background route for EXIF-rotated photos
- Change default background removal model from u2net to birefnet-general-lite
- Fix flaky test by setting SQLite busy_timeout before journal_mode pragma

Co-authored-by: Siddharth Kumar Sah <siddharth123sk@gmail.com>

packages/ai/python/remove_bg.py

@@ -14,7 +14,7 @@ def main():
     output_path = sys.argv[2]
     settings = json.loads(sys.argv[3]) if len(sys.argv) > 3 else {}
 
-    model = settings.get("model", "u2net")
+    model = settings.get("model", "birefnet-general-lite")
     bg_color = settings.get("backgroundColor", "")
 
     # Redirect stdout to stderr so library download/progress output