feat: Add search and filter UI components

- Created SearchBar component with debounced input
- Built FilterPanel component with controls for priority, completion, tags, and due date
- Added sort controls (field and direction)
- Implemented filter clear functionality
- Display search results with highlighted text
- Added GlobalSearch component for home page
- Integrated search and filter into list detail view
- Added CSS styles for search highlighting

Requirements: 6.1, 6.2, 6.3, 6.4, 8.1, 8.2, 8.3

app/page.tsx

@@ -1,6 +1,7 @@
 import { getLists } from '@/lib/actions'
 import ListCard from '@/components/ListCard'
 import NewListButton from '@/components/NewListButton'
+import GlobalSearch from '@/components/GlobalSearch'
 
 export default async function Home() {
   const lists = await getLists()
@@ -12,6 +13,11 @@ export default async function Home() {
         <NewListButton />
       </div>
 
+      {/* Global Search */}
+      <div className="mb-8">
+        <GlobalSearch />
+      </div>
+
       <div className="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-3 gap-6">
         {lists.map((list) => (
           <ListCard key={list.id} list={list} />