feat: implement global CSS styling and create AudioPlayer component

frontend/src/styles/globals.css

@@ -243,8 +243,18 @@ h1, h2, h3, h4 {
 .animate-aura       { animation: aura-pulse 10s ease-in-out infinite; }
 .animate-glow-beat  { animation: glow-beat  3s ease-in-out infinite; }
 .animate-spin-slow  { animation: spin-slow  10s linear infinite; }
+.animate-spin-paused { animation-play-state: paused; }
 .animate-ping-slow  { animation: ping-slow  2.5s cubic-bezier(0, 0, 0.2, 1) infinite; }
 
+@keyframes eq-bar {
+  0%, 100% { transform: scaleY(0.25); }
+  50%       { transform: scaleY(1); }
+}
+.animate-eq-bar {
+  animation: eq-bar 0.9s ease-in-out infinite;
+  transform-origin: bottom;
+}
+
 /* ── Shimmer loading skeleton ── */
 .shimmer {
   background: linear-gradient(