refactor(modules): improve exception handling and simplify service usage

Enhancements
- Replace bare `except:` with `except Exception:` in multiple modules- Cast step calculation to `int` for consistent type
- Simplify `get_battery_icon_file` to return a string directly
- Use `get_todo_service()` instead of module-level `todo_service` throughout todo widget
- Remove unused `"zen": "zen-browser"` mapping entry

Bug Fixes
- Prevent bare exception swallowing by catching `Exception` explicitly
- Ensure proper cleanup of timer IDs and other resources
- Delete unused modules/osdd components

New Features
- None

modules/notification/notification_center.py

@@ -170,7 +170,7 @@ class ExpandableNotificationGroup(Box):
     def _get_notification_pixbuf_for_group(self, cached_notification):
         """Get notification pixbuf using cached image key - fallback to app icon"""
         notification = cached_notification._notification
-        notification_id = getattr(notification, "id", None)
+        getattr(notification, "id", None)
 
         # First try to get cached notification image using stored cache key
         if (
@@ -447,7 +447,7 @@ class NotificationCenterWidget(NotificationWidget):
 
     def _get_notification_pixbuf(self, notification):
         """Get notification pixbuf using cached image key - fallback to app icon"""
-        notification_id = getattr(notification, "id", None)
+        getattr(notification, "id", None)
 
         # First try to get cached notification image using stored cache key
         if self.cache_metadata:
@@ -689,7 +689,7 @@ class NotificationCenter(Window):
         rebuild_count = 0
         for cached_notification in notification_service.cached_notifications:
             app_name = cached_notification._notification.app_name
-            notification_id = getattr(cached_notification._notification, "id", None)
+            getattr(cached_notification._notification, "id", None)
 
             # Skip ignored apps during rebuild
             if app_name in data.NOTIFICATION_IGNORED_APPS_HISTORY: