/play: Download dialog controls are not reachable via keyboard

[CarlosFelipeOR]

Describe the bug

The /play Download dialog is not fully keyboard accessible.
The main Download button can be reached with Tab and activated with Enter/Space. However, once the dialog is opened, keyboard navigation does not enter the dialog.
The dialog contains a file format dropdown and another Download button, but these controls cannot be reached using only the keyboard. Pressing Tab continues moving focus through the controls on the underlying /play page, as if the dialog was not open.
This prevents keyboard-only users from selecting a file format and completing the download flow.

To Reproduce

Steps to reproduce the behavior:

1. Open /play.
2. Run a query with results, for example:

   SELECT number FROM numbers(10)

3. Use Tab to focus the main Download button.
4. Press Enter or Space to open the Download dialog.
5. Press Tab again.

Expected behavior

After the Download dialog opens, keyboard focus should move into the dialog or Tab navigation should enter the dialog controls.
The file format dropdown and the Download button inside the dialog should be reachable and usable with the keyboard.

Actual behavior

The Download dialog opens, but keyboard focus stays on the underlying page.
Pressing Tab continues navigating the main /play page instead of moving through the dialog controls. As a result, the file format dropdown and the dialog Download button cannot be accessed using only the keyboard.

Versions affected

• 26.1.11.20001.altinityantalya
• 26.3.9.20001.altinityantalya