[Bug]: Project picker stays open after selecting a project in create issue dialog

[beastpu]

Deployment type

Official App

What happened?

When selecting a project in the manual or quick create-issue dialog, the selected project is applied but the project dropdown remains open.

The dropdown should close immediately after the selection, matching the status, priority, assignee, and label pickers.

This affects the shared create-issue UI used by both the web and desktop apps.

Steps to reproduce

1. Open the manual or quick create-issue dialog.
2. Click the project field.
3. Select any project.
4. Observe that the project value updates, but the dropdown remains visible.

Screenshots (optional)

A project remains checked in the still-open dropdown after selection.

Additional context (optional)

The create-issue dialogs pass open={fieldPickerOpen === "project" ? true : undefined} to ProjectPicker. After an item is selected, Base UI requests the menu to close and the parent changes the prop from true to undefined. The menu then retains its previously controlled open state instead of treating undefined as closed.

Normalizing the picker to always pass a boolean open value fixes the issue while preserving its uncontrolled/default-open usages.

[WitMiao]

Thanks for the detailed report — this matches the semi-controlled \open\ prop issue you described. Fix in #5668.