feat: remove TaskStats from HomePageClient and Header components

- Eliminated `initialStats` prop from `HomePageClient` and `KanbanPageClient` to streamline data handling.
- Updated `Header` and `HeaderContainer` components to remove references to `stats`, enhancing clarity and reducing unnecessary complexity.
- Adjusted `useTasks` hook to make `stats` optional, ensuring compatibility with the updated components.

hooks/useTasks.ts

@@ -25,7 +25,7 @@ interface UseTasksActions {
  */
 export function useTasks(
   initialFilters?: TaskFilters, 
-  initialData?: { tasks: Task[]; stats: TaskStats }
+  initialData?: { tasks: Task[]; stats?: TaskStats }
 ): UseTasksState & UseTasksActions {
   const [state, setState] = useState<UseTasksState>({
     tasks: initialData?.tasks || [],