Switch to hue-rotate animation for background gradient

- Revert complex conical gradient approach
- Return to original linear gradient (pink-100 → purple-50 → indigo-100)
- Add hue-rotate filter animation cycling through 360 degrees
- 8s duration for fast testing
- Simpler implementation with continuous color shifting
- Less control over saturation but smoother performance

examples/chat-ui/src/components/ChatApp.tsx

@@ -102,7 +102,7 @@ const ChatApp: React.FC<ChatAppProps> = () => {
   };
 
   return (
-    <div className="flex h-dvh w-screen overflow-clip animated-gradient-bg">
+    <div className="flex h-dvh w-screen overflow-clip bg-gradient-to-br from-pink-100 via-purple-50 to-indigo-100 animated-hue-bg">
       <div className="flex flex-row flex-grow flex-1 overflow-hidden relative">
         {/* Sidebar and Navbar components hidden but kept in codebase */}
         {false && (