Add smooth animations across WebUI for modern feel

- Tab panels: fade-in with subtle translateY on switch
- Cards: hover lift (translateY -2px), staggered entrance animation
- Modals: spring-curve entrance with backdrop blur
- Buttons: press feedback (scale down on :active)
- Toggle switches: spring overshoot on knob transition
- Toast: smooth bounce-in replaces jarring shake
- Sections: animated height collapse/expand with chevron rotation
- Command palette: slide-down entrance animation
- Theme switch: smooth color transitions on key elements
- Dashboard: section collapse animation, target row hover
- Respects prefers-reduced-motion globally

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/wled_controller/static/css/modal.css

@@ -11,6 +11,7 @@
     align-items: center;
     justify-content: center;
     animation: fadeIn 0.2s ease-out;
+    backdrop-filter: blur(2px);
 }
 
 /* Confirm dialog must stack above all other modals */
@@ -132,7 +133,7 @@
     display: flex;
     flex-direction: column;
     box-shadow: 0 8px 32px var(--shadow-color);
-    animation: slideUp 0.3s ease-out;
+    animation: slideUp 0.3s cubic-bezier(0.16, 1, 0.3, 1);
 }
 
 #template-modal .modal-content {
@@ -146,11 +147,11 @@
 
 @keyframes slideUp {
     from {
-        transform: translateY(20px);
+        transform: translateY(20px) scale(0.98);
         opacity: 0;
     }
     to {
-        transform: translateY(0);
+        transform: translateY(0) scale(1);
         opacity: 1;
     }
 }
@@ -479,7 +480,7 @@
     content: '▶';
     font-size: 0.6rem;
     opacity: 0.6;
-    transition: transform 0.15s;
+    transition: transform 0.2s cubic-bezier(0.4, 0, 0.2, 1);
     flex-shrink: 0;
 }