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/pages/Home.tsx

@@ -120,7 +120,7 @@ export default function Home() {
             {isVisible('discover') && (
               <AlbumRow
                 title={t('home.discover')}
-                titleLink="/random-albums"
+                titleLink="/random/albums"
                 albums={random}
                 onLoadMore={() => loadMore('random', random, setRandom)}
                 moreText={t('home.discoverMore')}

src/pages/RandomLanding.tsx

@@ -0,0 +1,52 @@
+import React from 'react';
+import { useNavigate } from 'react-router-dom';
+import { useTranslation } from 'react-i18next';
+import { Shuffle, Dices } from 'lucide-react';
+
+interface MixCard {
+  icon: React.ElementType;
+  labelKey: string;
+  descKey: string;
+  to: string;
+}
+
+const CARDS: MixCard[] = [
+  {
+    icon: Shuffle,
+    labelKey: 'randomLanding.mixByTracks',
+    descKey:  'randomLanding.mixByTracksDesc',
+    to: '/random/mix',
+  },
+  {
+    icon: Dices,
+    labelKey: 'randomLanding.mixByAlbums',
+    descKey:  'randomLanding.mixByAlbumsDesc',
+    to: '/random/albums',
+  },
+];
+
+export default function RandomLanding() {
+  const { t } = useTranslation();
+  const navigate = useNavigate();
+
+  return (
+    <div className="random-landing">
+      <div className="random-landing-grid">
+        {CARDS.map(({ icon: Icon, labelKey, descKey, to }) => (
+          <button
+            key={to}
+            className="mix-pick-card"
+            onClick={() => navigate(to)}
+          >
+            <Icon className="mix-pick-card-bg-icon" strokeWidth={1} aria-hidden />
+            <div className="mix-pick-card-content">
+              <Icon size={28} strokeWidth={1.5} className="mix-pick-card-icon" aria-hidden />
+              <span className="mix-pick-card-label">{t(labelKey)}</span>
+              <span className="mix-pick-card-desc">{t(descKey)}</span>
+            </div>
+          </button>
+        ))}
+      </div>
+    </div>
+  );
+}