Add safe database migration workflow and note history infrastructure.

This introduces guarded migrations with automatic backups, fixes note creation after DB reset, and wires snapshot/restore history across notes surfaces.

Momento-main/momento/memento-note/app/api/notes/[id]/history/route.ts

@@ -0,0 +1,51 @@
+import { NextRequest, NextResponse } from 'next/server'
+import { auth } from '@/auth'
+import { getNoteHistory, restoreNoteVersion } from '@/app/actions/notes'
+
+export async function GET(
+  request: NextRequest,
+  { params }: { params: Promise<{ id: string }> }
+) {
+  const session = await auth()
+  if (!session?.user?.id) {
+    return NextResponse.json({ success: false, error: 'Unauthorized' }, { status: 401 })
+  }
+
+  try {
+    const { id } = await params
+    const limitRaw = request.nextUrl.searchParams.get('limit')
+    const limit = limitRaw ? Number.parseInt(limitRaw, 10) : 30
+    const entries = await getNoteHistory(id, Number.isNaN(limit) ? 30 : limit)
+    return NextResponse.json({ success: true, data: entries })
+  } catch (error) {
+    console.error('Error fetching note history:', error)
+    return NextResponse.json({ success: false, error: 'Failed to fetch history' }, { status: 500 })
+  }
+}
+
+export async function POST(
+  request: NextRequest,
+  { params }: { params: Promise<{ id: string }> }
+) {
+  const session = await auth()
+  if (!session?.user?.id) {
+    return NextResponse.json({ success: false, error: 'Unauthorized' }, { status: 401 })
+  }
+
+  try {
+    const { id } = await params
+    const body = await request.json()
+    const historyEntryId = body?.historyEntryId
+
+    if (!historyEntryId || typeof historyEntryId !== 'string') {
+      return NextResponse.json({ success: false, error: 'historyEntryId is required' }, { status: 400 })
+    }
+
+    const restoredNote = await restoreNoteVersion(id, historyEntryId)
+    return NextResponse.json({ success: true, data: restoredNote })
+  } catch (error) {
+    const message = error instanceof Error ? error.message : 'Failed to restore history version'
+    console.error('Error restoring note history:', error)
+    return NextResponse.json({ success: false, error: message }, { status: 500 })
+  }
+}