fix(i18n): add common.play key to all 8 locales (fix for PR #186)

The AlbumHeader and PlaylistDetail play buttons use t('common.play') which
was missing — 'Reproducir' would have appeared as fallback in all languages.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/locales/en.ts

@@ -388,6 +388,7 @@ export const enTranslation = {
     filterSearchGenres: 'Search genres…',
     filterNoGenres: 'No genres match',
     filterClear: 'Clear',
+    play: 'Play',
     bulkSelected: '{{count}} selected',
     clearSelection: 'Clear selection',
     bulkAddToPlaylist: 'Add to Playlist',