feat: implement UI-3D state consistency switcher for week 3 task 3 in r3f

Week-3/Task-3/r3f/src/App.css

@@ -4,6 +4,45 @@
   position: relative;
   background-color: white;
   overflow: hidden;
+  font-family: 'Inter', system-ui, -apple-system, sans-serif;
+}
+
+#controls {
+  position: absolute;
+  top: 20px;
+  left: 20px;
+  z-index: 10;
+  display: flex;
+  gap: 12px;
+  background: rgba(255, 255, 255, 0.8);
+  backdrop-filter: blur(10px);
+  padding: 16px;
+  border-radius: 12px;
+  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
+  border: 1px solid rgba(0, 0, 0, 0.05);
+}
+
+button {
+  padding: 10px 18px;
+  border: none;
+  border-radius: 8px;
+  background: white;
+  color: #333;
+  cursor: pointer;
+  font-weight: 500;
+  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
+  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.05);
+}
+
+button:hover {
+  transform: translateY(-2px);
+  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
+}
+
+button.active {
+  background: #333;
+  color: white;
+  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
 }
 
 .canvas-wrapper {

Week-3/Task-3/r3f/src/App.jsx

@@ -15,6 +15,10 @@ const variants = {
   gold: {
     geometry: <torusGeometry args={[1.2, 0.4, 16, 100]} />,
     material: { color: "#FFD700", roughness: 0.4, metalness: 1 }
+  },
+  emerald: {
+    geometry: <cylinderGeometry args={[1.2, 0.4, 2.5, 32]} />,
+    material: { color: "#009B77", roughness: 0.4, metalness: 1 }
   }
 };