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/locales/de.ts

@@ -99,6 +99,8 @@ export const deTranslation = {
     playNext: 'Als Nächstes abspielen',
     addToQueue: 'Zur Warteschlange hinzufügen',
     enqueueAlbum: 'Ganzes Album einreihen',
+    enqueueAlbums_one: '{{count}} Album einreihen',
+    enqueueAlbums_other: '{{count}} Alben einreihen',
     startRadio: 'Radio starten',
     instantMix: 'Instant Mix',
     instantMixFailed: 'Instant Mix konnte nicht erstellt werden — Server- oder Pluginfehler.',
@@ -303,6 +305,10 @@ export const deTranslation = {
     selectionCount: '{{count}} ausgewählt',
     downloadZips: 'ZIPs herunterladen',
     addOffline: 'Offline hinzufügen',
+    enqueueSelected_one: 'Einreihen ({{count}})',
+    enqueueSelected_other: 'Einreihen ({{count}})',
+    enqueueQueued_one: '{{count}} Album zur Warteschlange hinzugefügt',
+    enqueueQueued_other: '{{count}} Alben zur Warteschlange hinzugefügt',
     downloadingZip: 'Lade {{current}}/{{total}} herunter: {{name}}',
     downloadZipDone: '{{count}} ZIP(s) heruntergeladen',
     downloadZipFailed: 'Download fehlgeschlagen: {{name}}',