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

components/GlobalSearch.tsx

@@ -0,0 +1,71 @@
+'use client'
+
+import { useState, useCallback } from 'react'
+import SearchBar from './SearchBar'
+import SearchResults from './SearchResults'
+import { searchItems } from '@/lib/actions'
+
+interface ItemWithList {
+  id: string
+  title: string
+  description: string | null
+  completed: boolean
+  priority: string
+  dueDate: Date | null
+  tags: any
+  notes: string | null
+  list: {
+    id: string
+    title: string
+    color: string
+  }
+}
+
+export default function GlobalSearch() {
+  const [searchQuery, setSearchQuery] = useState('')
+  const [searchResults, setSearchResults] = useState<ItemWithList[]>([])
+  const [isSearching, setIsSearching] = useState(false)
+
+  const handleSearch = useCallback(async (query: string) => {
+    setSearchQuery(query)
+    
+    if (!query.trim()) {
+      setSearchResults([])
+      setIsSearching(false)
+      return
+    }
+
+    setIsSearching(true)
+    try {
+      const results = await searchItems(query)
+      setSearchResults(results as ItemWithList[])
+    } catch (error) {
+      console.error('Search error:', error)
+      setSearchResults([])
+    } finally {
+      setIsSearching(false)
+    }
+  }, [])
+
+  const handleClose = useCallback(() => {
+    setSearchQuery('')
+    setSearchResults([])
+  }, [])
+
+  return (
+    <div className="space-y-4">
+      <SearchBar 
+        onSearch={handleSearch}
+        placeholder="Search all tasks..."
+      />
+
+      {searchQuery.trim() && (
+        <SearchResults 
+          results={searchResults}
+          query={searchQuery}
+          onClose={handleClose}
+        />
+      )}
+    </div>
+  )
+}