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/en.ts

@@ -5,6 +5,7 @@ export const enTranslation = {
     newReleases: 'New Releases',
     allAlbums: 'All Albums',
     randomAlbums: 'Random Albums',
+    randomPicker: 'Build a Mix',
     artists: 'Artists',
     randomMix: 'Random Mix',
     favorites: 'Favorites',
@@ -204,6 +205,13 @@ export const enTranslation = {
     removeSong: 'Remove from favorites',
     stations: 'Radio Stations',
   },
+  randomLanding: {
+    title: 'Build a Mix',
+    mixByTracks: 'Mix by Tracks',
+    mixByTracksDesc: 'Random selection of tracks from your entire library',
+    mixByAlbums: 'Mix by Albums',
+    mixByAlbumsDesc: 'Random album picks for your next discovery',
+  },
   randomAlbums: {
     title: 'Random Albums',
     refresh: 'Refresh',