feat(albums): compilation filter toggle in All Albums

Tri-state button (all / only compilations / hide compilations) in the
Albums page header, using the OpenSubsonic isCompilation tag from
Navidrome. Client-side filter via useMemo, no extra server calls.
Closes #65.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/locales/de.ts

@@ -290,6 +290,12 @@ export const deTranslation = {
     yearTo: 'Bis',
     yearFilterClear: 'Jahresfilter zurücksetzen',
     yearFilterLabel: 'Jahr',
+    compilationLabel: 'Sampler',
+    compilationOnly: 'Nur Sampler',
+    compilationHide: 'Ohne Sampler',
+    compilationTooltipAll: 'Alle Alben · klicken: nur Sampler',
+    compilationTooltipOnly: 'Nur Sampler · klicken: Sampler ausblenden',
+    compilationTooltipHide: 'Sampler ausgeblendet · klicken: alle zeigen',
     select: 'Mehrfachauswahl',
     startSelect: 'Mehrfachauswahl aktivieren',
     cancelSelect: 'Abbrechen',