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/api/schemas.py

@@ -50,10 +50,6 @@ class TaskUpdateRequest(BaseModel):
     pinned: bool | None = None
 
 
-class TaskDoneRequest(BaseModel):
-    done: bool = True
-
-
 class BlockEventRequest(BaseModel):
     kind: Literal["domain", "app"] = "domain"
     target: str = Field(min_length=1, max_length=255)