[Bug] Plugin pane loses keyboard focus after prompt interaction and cannot regain it via clicks

Bug Description
Clicking a plugin pane no longer gives it keyboard focus after the prompt takes it (regression since 2.1.289)
▎ Claude Code 2.1.295 and 2.1.296, Ghostty, macOS. It worked on 2.1.289.
▎ 1. A plugin opens a pane with $.ui.open({ id, focus: true }); its Buttons have hotkeys, and clicks and hotkeys work.
▎ 2. Type a letter at the prompt, or switch to another terminal window and back.
▎ 3. Click inside the pane.
▎
▎ Expected: the pane gets the keys back, as the plugin docs say ("holds it after ctrl+x tab, a click or open({ focus })").
▎ Actual: the pane stays unfocused and ignores clicks and hotkeys. Only a new open({ focus: true }) from a slash command with an empty prompt restores it. Plugins can't work around it: a pane root has no press or focus event, and $.ui.focus is denied without the keys.

Environment Info

• Platform: darwin
• Terminal: ghostty
• Version: 2.1.289
• Feedback ID: d4088ceb-fad7-4b77-a016-a320b07043de