Initial commit: accountbook project

- Node.js backend server
- Frontend application
- Backup script
- Project specification

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/pages/_app.js

@@ -0,0 +1,13 @@
+import '../styles/globals.css';
+import { ToastProvider } from '../components/ToastProvider';
+import { ConfirmProvider } from '../components/ConfirmProvider';
+
+export default function App({ Component, pageProps }) {
+  return (
+    <ConfirmProvider>
+      <ToastProvider>
+        <Component {...pageProps} />
+      </ToastProvider>
+    </ConfirmProvider>
+  );
+}