refactor: enhance TimerPage layout and functionality; update theme and tokens for improved design consistency

- Refactored TimerPage component to improve layout and user experience.
- Updated theme configuration to utilize design tokens for better maintainability.
- Introduced new tokens for colors and typography to align with design principles.
- Simplified state management and improved timer functionality.
- Enhanced accessibility and responsiveness of UI elements.

backend/app/sources/laundry.py

@@ -133,9 +133,6 @@ class LaundrySource:
         self._check_session()
         return f"signed in at {self._base_url}"
 
-    def complete(self, item: TodoItem) -> bool:
-        return False  # the washing machine finishes on its own
-
     def close(self) -> None:
         self._client.close()