Major UI improvements and cleanup

✨ Features:
- Add movable theme button with drag functionality
- Theme button rotation animation on toggle
- Position persistence across page reloads
- Remove flash positioning on page load

🗑️ Cleanup:
- Remove URL shortener functionality completely
- Unify expiry dropdown (remove duplicate from pastebin)
- Fix import issues in cleanup scripts and app.py
- Remove unused CSS and JavaScript code

🔧 Technical:
- Improve drag vs click detection
- Add viewport boundary constraints for theme button
- Clean up JavaScript event handlers
- Optimize CSS animations and transitions

cleanup_expired.py

@@ -9,12 +9,12 @@ import json
 from datetime import datetime, timezone
 from pathlib import Path
 
-# Add src directory to Python path
-src_path = Path(__file__).parent / "src"
-sys.path.insert(0, str(src_path))
+# Add the project root to Python path
+project_root = Path(__file__).parent
+sys.path.append(str(project_root))
 
-from config import config
-from storage import StorageManager
+from src.config import config
+from src.storage import StorageManager
 
 
 def cleanup_local_storage(storage_manager):