feat(albums): add 'Enqueue' option to album cover, context menu and multi-select toolbar (closes #253) (#256)

Per bcorporaal's request in #253: making a queue from multiple albums
required either replacing the queue (Play) or going into each album
detail page first. Three new entry points cover the common workflows:

1. Hover button on the album cover next to Play. Both buttons share
   the same accent style and size so the secondary action is just as
   readable as the primary — first attempt with a darker pill was hard
   to see and unbalanced the hover.

2. Context-menu entry "Enqueue Album" between "Open Album" and "Go to
   Artist". The i18n key already existed (was used by the album-song
   sub-context); just wiring up the action.

3. Multi-select toolbar in Albums.tsx: new "Enqueue (N)" button placed
   before "Add Offline" so power users selecting several albums no
   longer have to right-click. Plus a context-menu entry "Enqueue N
   Albums" for the same flow when a multi-album right-click happens
   anywhere else.

All multi-album fetches use Promise.all(getAlbum(...)) — Navidrome
handles parallel requests instantly (per memory note from PR #246).

i18n: 4 new keys per locale (3 with pluralisation: contextMenu.enqueueAlbums,
albums.enqueueSelected, albums.enqueueQueued).

Co-authored-by: Psychotoxical <dev@psysonic.app>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/ContextMenu.tsx

@@ -1649,6 +1649,12 @@ export default function ContextMenu() {
               <div className="context-menu-item" onClick={() => handleAction(() => navigate(`/album/${album.id}`))}>
                 <Play size={14} /> {t('contextMenu.openAlbum')}
               </div>
+              <div className="context-menu-item" onClick={() => handleAction(async () => {
+                const albumData = await getAlbum(album.id);
+                enqueue(albumData.songs.map(songToTrack));
+              })}>
+                <ListPlus size={14} /> {t('contextMenu.enqueueAlbum')}
+              </div>
               <div className="context-menu-divider" />
               <div className="context-menu-item" onClick={() => handleAction(() => navigate(`/artist/${album.artistId}`))}>
                 <User size={14} /> {t('contextMenu.goToArtist')}
@@ -1751,6 +1757,14 @@ export default function ContextMenu() {
                 {t('contextMenu.selectedAlbums', { count: albums.length })}
               </div>
               <div className="context-menu-divider" />
+              <div className="context-menu-item" onClick={() => handleAction(async () => {
+                // Parallel — Navidrome handles concurrent getAlbum requests fine.
+                const results = await Promise.all(albums.map(a => getAlbum(a.id)));
+                const allTracks = results.flatMap(r => r.songs.map(songToTrack));
+                enqueue(allTracks);
+              })}>
+                <ListPlus size={14} /> {t('contextMenu.enqueueAlbums', { count: albums.length })}
+              </div>
               <div
                 className={`context-menu-item context-menu-item--submenu ${playlistSubmenuOpen && playlistSongIds[0] === `multi-album:${albumIds.join(',')}` ? 'active' : ''}`}
                 data-playlist-trigger-id={`multi-album:${albumIds.join(',')}`}