move inline animations to Tailwind config

Optimization #11:
- added float-1, float-2, float-3 animation variants to tailwind.config.js
- replaced inline animation and animationDelay styles with Tailwind classes
- use modulo pattern to cycle through 3 animation variants
- maintains visual variety without Math.random() for animation timing
- consistent with Tailwind conventions, easier to maintain

src/pages/Results.tsx

···
       <div className="bg-firefly-banner dark:bg-firefly-banner-dark text-white relative overflow-hidden">
         {!reducedMotion && (
           <div className="absolute inset-0 opacity-20" aria-hidden="true">
-            {[...Array(10)].map((_, i) => (
-              <div
-                key={i}
-                className="absolute w-1 h-1 bg-white rounded-full"
-                style={{
-                  left: `${Math.random() * 100}%`,
-                  top: `${Math.random() * 100}%`,
-                  animation: `float ${2 + Math.random()}s ease-in-out infinite`,
-                  animationDelay: `${Math.random()}s`,
-                }}
-              />
-            ))}
+            {[...Array(10)].map((_, i) => {
+              const animations = ["animate-float-1", "animate-float-2", "animate-float-3"];
+              return (
+                <div
+                  key={i}
+                  className={`absolute w-1 h-1 bg-white rounded-full ${animations[i % 3]}`}
+                  style={{
+                    left: `${Math.random() * 100}%`,
+                    top: `${Math.random() * 100}%`,
+                  }}
+                />
+              );
+            })}
           </div>
         )}
         <div className="max-w-3xl mx-auto px-4 py-6 relative">

tailwind.config.js

···
       }),
       animation: {
         float: "float 3s ease-in-out infinite",
+        "float-1": "float 2s ease-in-out infinite",
+        "float-2": "float 2.5s ease-in-out 0.3s infinite",
+        "float-3": "float 3s ease-in-out 0.6s infinite",
       },
       keyframes: {
         float: {