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

mcp-server/node_modules/.prisma/client/schema.prisma

@@ -0,0 +1,25 @@
+generator client {
+  provider = "prisma-client-js"
+  output   = "../node_modules/.prisma/client"
+}
+
+datasource db {
+  provider = "sqlite"
+  url      = "file:../../keep-notes/prisma/dev.db"
+}
+
+model Note {
+  id         String   @id @default(cuid())
+  title      String?
+  content    String
+  color      String   @default("default")
+  type       String   @default("text")
+  checkItems String?
+  labels     String?
+  images     String?
+  isPinned   Boolean  @default(false)
+  isArchived Boolean  @default(false)
+  order      Int      @default(0)
+  createdAt  DateTime @default(now())
+  updatedAt  DateTime @updatedAt
+}