fix: Add debounced Undo/Redo system to avoid character-by-character history

- Add debounced state updates for title and content (500ms delay)
- Immediate UI updates with delayed history saving
- Prevent one-letter-per-undo issue
- Add cleanup for debounce timers on unmount

keep-notes/app/page.tsx

@@ -0,0 +1,23 @@
+import { getNotes, searchNotes } from '@/app/actions/notes'
+import { NoteInput } from '@/components/note-input'
+import { NoteGrid } from '@/components/note-grid'
+
+export const dynamic = 'force-dynamic'
+
+export default async function HomePage({
+  searchParams,
+}: {
+  searchParams: Promise<{ search?: string }>
+}) {
+  const params = await searchParams
+  const notes = params.search
+    ? await searchNotes(params.search)
+    : await getNotes()
+
+  return (
+    <main className="container mx-auto px-4 py-8 max-w-7xl">
+      <NoteInput />
+      <NoteGrid notes={notes} />
+    </main>
+  )
+}