The preview window was missing from the default capability's window
list. Its frontend calls core:window:allow-hide (getCurrentWindow().hide()
on dismiss / auto-hide) plus invoke('copy_to_clipboard') and a handful
of event listeners — none of those would have been permitted at runtime
because the capability never matched this window's label.
Add 'transcription-preview' alongside the other secondary windows so
the preview actually has access to the permissions it already relies on.
Regenerate gen/schemas/capabilities.json to match.
Co-authored-by: jars <jakejars@users.noreply.github.com>
74062f8381