The hover watched-toggle on Plex movie/episode cards is icon-only (WatchedIcon,
no text), so it carried a `title` but no accessible name for screen readers —
and the empty-Circle unwatched glyph could read like a radio. Mirror the title
into `aria-label` (the Modal close-button idiom) so the control announces its
action. The PlexInfo watched buttons already have visible text labels, so they
need nothing.
FE gate green (tsc/eslint/prettier/knip, 309 vitest).