fix(ui): reserve popup header space for controls - #955

On December 2, 2026, GitHub will restrict `pull_request_target` on public repositories by default. To continue allowing the event trigger, configure an Actions policy. Learn more: https://gh.io/securely-using-pull_request_target#default-policy-for-pull_request_target

⚠️ SECURITY WARNING: Bypassing write permission check for deniial00 due to allowed_non_write_users='*'. This should only be used for workflows with very limited permissions.