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/google_tasks.py

@@ -142,25 +142,6 @@ class GoogleTasksSource:
     def check(self) -> str:
         return f"{len(self._task_lists())} Google task list(s) visible"
 
-    def complete(self, item: TodoItem) -> bool:
-        """PATCH the task's status — Google Tasks has no dedicated close verb."""
-        if not self._config.writeback_done:
-            return False
-        list_id, _, task_id = item.external_id.partition(":")
-        if not (list_id and task_id):
-            raise SourceError(f"Unusable Google task id: {item.external_id!r}")
-        try:
-            resp = self._client.patch(
-                f"{_API_BASE}/lists/{list_id}/tasks/{task_id}",
-                json={"status": "completed"},
-                headers={"Authorization": f"Bearer {self._token()}"},
-            )
-        except httpx.HTTPError as exc:
-            raise SourceError(f"Google is unreachable: {exc}") from exc
-        if not resp.is_success:
-            raise SourceError(f"Google could not complete the task: {resp.status_code}")
-        return True
-
     def close(self) -> None:
         self._client.close()