feat: add image opacity, config migration, settings

Add image overlay opacity support and related UI/settings, plus robust config migration and error handling.

Key changes:
- UI: image overlay now uses QGraphicsOpacityEffect, hides when disabled, and updates opacity on state changes (src/interface/dialogs/image.py).
- New NotificationPopup dialog for user alerts (src/interface/dialogs/notificationpopup.py).
- Settings dialog: added Image Opacity control, adjusted labels, persist/rollback behavior on cancel, and include opacity when saving (src/interface/dialogs/settings.py).
- State: added properties for image_opacity and image_enabled with change notifications; renamed image_width setter param for clarity (src/utils/data/state.py).
- Config: switch from config.yml to config.ini, implement one-time migration, typed read/write of values, validation/error handling, automatic backups of corrupted files and user notification (src/utils/config/config.py).
- Settings save: accept and persist image_opacity (src/utils/config/settings.py).
- Startup: initialize QApplication earlier and pass app to run_gui (src/main.py).
- Minor: removed an extra blank line in log handler and small import cleanups.

These changes enable adjustable overlay transparency, improve config reliability, and surface errors to users while preserving/backuping old configs.

src/utils/logging/loghandler.py

@@ -3,7 +3,6 @@ from utils.logging.logs import consoleLog, remove_download_log
 import os
 
 def split_data(data):
-
     count = data.count
     downloads = data.data