Expiration date picker: selecting a month doesn’t navigate to that month (requires manual “Back to date selection”)

**Is your feature request related to a problem? Please describe.**

When creating a Personal Access Token, the expiration date picker has a month selection view. After selecting a month, the UI does **not** automatically navigate to the corresponding month’s calendar (day selection view). Users must manually click **“Back to date selection”** to return to the calendar view.

This breaks the expected flow (month selection → day selection) and feels unintuitive, because the “Back” action becomes a required step to continue.

**Steps to reproduce**

1. Open **Coze Studio** and go to **Personal Access Token** creation.
2. Click **Add new Personal Access Token**.
3. In **Expiration time**, choose **Custom**.
4. Open the date picker, switch to the **month selection** view (year/month list).
5. Select any month (e.g., **May 2029**).

**Actual behavior**

* The UI stays on the month selection view after clicking a month.
* User must manually click **“Back to date selection”** to return to the calendar/day view, then pick a specific date.

**Expected behavior**

* After selecting a month, the date picker should automatically switch to the calendar/day view and display the selected month, so the user can immediately pick a day.

**Describe the solution you'd like**

* Auto-navigate to the chosen month after a month is clicked:

* Month selected → automatically return to calendar/day picker → show the selected month.
* (Optional) Keep a clear header/breadcrumb like **“2029 / May”** to confirm current context.

**Describe alternatives you've considered**

1. Add a **“Confirm/Next”** button in the month selection view (instead of requiring “Back to date selection”).
2. Keep the month selection view, but allow selecting a month to **auto-close** the month list and return to the day view immediately.
3. Make the header clickable to toggle between month view and day view (common date picker pattern).

**Additional context**

* Occurs in the “Add new Personal Access Token” modal’s expiration date picker.
* Screenshot attached (month selection view shows “Back to date selection”; selecting a month does not navigate automatically).

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Start by reproducing the issue in the Personal Access Token creation modal, under Expiration time → Custom, and inspect the date picker’s month selection flow. Done means selecting a month immediately returns to the calendar/day view and displays that month so a day can be chosen without clicking “Back to date selection”.

Written by the indexing model from the issue text.