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/ajv/dist/runtime/validation_error.d.ts

@@ -0,0 +1,7 @@
+import type { ErrorObject } from "../types";
+export default class ValidationError extends Error {
+    readonly errors: Partial<ErrorObject>[];
+    readonly ajv: true;
+    readonly validation: true;
+    constructor(errors: Partial<ErrorObject>[]);
+}