feat: Add visual feedback and polish (Task 15)

- Implement toast notification system for success/error messages
- Add loading states with skeleton loaders for async operations
- Create smooth CSS transitions and animations
- Enhance empty states with EmptyState component
- Add loading.tsx files for Next.js loading states
- Integrate toast notifications across all CRUD operations
- Add fade-in and scale-in animations for better UX
- Improve visual feedback for user actions

components/SearchResults.tsx

@@ -3,6 +3,7 @@
 import { highlightText } from '@/lib/utils'
 import Link from 'next/link'
 import { Calendar, Tag, AlertCircle } from 'lucide-react'
+import EmptyState from './EmptyState'
 
 interface SearchResultsProps {
   results: Array<{
@@ -31,10 +32,11 @@ export default function SearchResults({ results, query, onClose }: SearchResults
 
   if (results.length === 0) {
     return (
-      <div className="bg-white rounded-lg border border-gray-200 p-8 text-center">
-        <p className="text-gray-500">No tasks found matching "{query}"</p>
-        <p className="text-sm text-gray-400 mt-2">Try a different search term</p>
-      </div>
+      <EmptyState
+        icon="search"
+        title={`No tasks found matching "${query}"`}
+        description="Try a different search term or check your spelling"
+      />
     )
   }
 
@@ -45,7 +47,7 @@ export default function SearchResults({ results, query, onClose }: SearchResults
   }
 
   return (
-    <div className="space-y-2">
+    <div className="space-y-2 animate-fade-in">
       <div className="flex items-center justify-between mb-4">
         <p className="text-sm text-gray-600">
           Found {results.length} {results.length === 1 ? 'task' : 'tasks'}