updated /quit to use new slash command arch (#4259)

Co-authored-by: Abhi <abhipatel@google.com>

packages/cli/src/ui/commands/quitCommand.ts

@@ -0,0 +1,35 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { formatDuration } from '../utils/formatters.js';
+import { type SlashCommand } from './types.js';
+
+export const quitCommand: SlashCommand = {
+  name: 'quit',
+  altName: 'exit',
+  description: 'exit the cli',
+  action: (context) => {
+    const now = Date.now();
+    const { sessionStartTime } = context.session.stats;
+    const wallDuration = now - sessionStartTime.getTime();
+
+    return {
+      type: 'quit',
+      messages: [
+        {
+          type: 'user',
+          text: `/quit`, // Keep it consistent, even if /exit was used
+          id: now - 1,
+        },
+        {
+          type: 'quit',
+          duration: formatDuration(wallDuration),
+          id: now,
+        },
+      ],
+    };
+  },
+};