fix: correct prefers-reduced-motion animation handling

- Remove duplicate @keyframes scan from reduced-motion block
- Properly disable animation classes (.animate-scan-fast, etc) for motion-sensitive users
- Maintain Tailwind keyframe definitions outside media query
- Respects accessibility preference while preserving animation system

frontend/app/globals.css

@@ -84,16 +84,8 @@ h1, h2, h3, h4, h5, h6 {
     transition-duration: 0.01ms !important;
   }
 
-  /* Disable keyframe animations */
-  @keyframes scan {
-    0%, 100% { top: 0%; }
-    50% { top: 100%; }
-  }
-
-  .animate-spin-slow {
-    animation: none !important;
-  }
-
+  .animate-scan-fast,
+  .animate-spin-slow,
   .animate-pulse {
     animation: none !important;
   }