fix: clean up unused imports in KanbanFilters and backup

- Removed unused `getToday` import from `backup.ts` to streamline the code.
- Cleaned up imports in `KanbanFilters.tsx` by removing `useMemo`, which was not utilized, enhancing readability.

src/components/kanban/KanbanFilters.tsx

@@ -1,6 +1,6 @@
 'use client';
 
-import { useState, useEffect, useRef, useMemo, useCallback } from 'react';
+import { useState, useEffect, useRef, useCallback } from 'react';
 import { createPortal } from 'react-dom';
 import { TaskPriority, TaskStatus } from '@/lib/types';
 import { Button } from '@/components/ui/Button';