Orphaned by the TV modal refactor: TVSubtitleSheet was an overlay sheet
introduced in c515d037 (unify subtitle selector + search into a tabbed sheet),
then de-wired in d545ca35 (fix(tv): modals) when the TV subtitle UI moved to the
navigation-based modal route (tv-subtitle-modal), per the project's TV-modal
guide. The import was removed but the file was left behind. No imports remain
(git grep), and every i18n key it used is also used by tv-subtitle-modal, so no
translation cleanup is needed.