feat: MVP-4 Sprint 3 - Version history

- Add NoteVersion model for storing note snapshots
- Add versions API (list, create, get, restore)
- Add version history UI dialog in note detail page
- Create version snapshot before each note update

src/app/api/notes/[id]/versions/[versionId]/route.ts

@@ -0,0 +1,23 @@
+import { NextRequest } from 'next/server'
+import { getVersion, restoreVersion } from '@/lib/versions'
+import { createErrorResponse, createSuccessResponse } from '@/lib/errors'
+
+export async function GET(req: NextRequest, { params }: { params: Promise<{ id: string; versionId: string }> }) {
+  try {
+    const { versionId } = await params
+    const version = await getVersion(versionId)
+    return createSuccessResponse(version)
+  } catch (error) {
+    return createErrorResponse(error)
+  }
+}
+
+export async function PUT(req: NextRequest, { params }: { params: Promise<{ id: string; versionId: string }> }) {
+  try {
+    const { id, versionId } = await params
+    const note = await restoreVersion(id, versionId)
+    return createSuccessResponse(note)
+  } catch (error) {
+    return createErrorResponse(error)
+  }
+}