feat(nav): merge Random Mix & Albums into Build a Mix hub

Replaces two sidebar entries (Random Mix, Random Albums) with a single 'Build a Mix' item (Wand2 icon) at /random. Landing page shows two cards — Mix by Tracks and Mix by Albums — with glow-on-hover. Old routes updated throughout. All 7 locales updated.

src/locales/nl.ts

@@ -5,6 +5,7 @@ export const nlTranslation = {
     newReleases: 'Nieuw',
     allAlbums: 'Alle albums',
     randomAlbums: 'Willekeurige albums',
+    randomPicker: 'Mix samenstellen',
     artists: 'Artiesten',
     randomMix: 'Willekeurige mix',
     favorites: 'Favorieten',
@@ -203,6 +204,13 @@ export const nlTranslation = {
     removeSong: 'Verwijderen uit favorieten',
     stations: 'Radiostations',
   },
+  randomLanding: {
+    title: 'Mix samenstellen',
+    mixByTracks: 'Mix op nummers',
+    mixByTracksDesc: 'Willekeurige selectie uit je volledige mediatheek',
+    mixByAlbums: 'Mix op albums',
+    mixByAlbumsDesc: 'Willekeurige albums voor nieuwe ontdekkingen',
+  },
   randomAlbums: {
     title: 'Willekeurige albums',
     refresh: 'Vernieuwen',