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/layout.css

@@ -133,7 +133,7 @@ h2 {
     cursor: pointer;
     border-bottom: 2px solid transparent;
     margin-bottom: -2px;
-    transition: color 0.2s, border-color 0.2s;
+    transition: color 0.2s ease, border-color 0.25s ease;
 }
 
 .tab-btn:hover {
@@ -171,6 +171,12 @@ h2 {
 
 .tab-panel.active {
     display: block;
+    animation: tabFadeIn 0.25s ease-out;
+}
+
+@keyframes tabFadeIn {
+    from { opacity: 0; transform: translateY(8px); }
+    to { opacity: 1; transform: translateY(0); }
 }
 
 /* Thin animated bar at top of tab panel during data refresh */
@@ -257,6 +263,7 @@ h2 {
     inset: 0;
     background: rgba(0, 0, 0, 0.5);
     backdrop-filter: blur(2px);
+    animation: fadeIn 0.15s ease-out;
 }
 
 .cp-dialog {
@@ -272,6 +279,12 @@ h2 {
     flex-direction: column;
     overflow: hidden;
     align-self: flex-start;
+    animation: cpSlideDown 0.2s cubic-bezier(0.16, 1, 0.3, 1);
+}
+
+@keyframes cpSlideDown {
+    from { opacity: 0; transform: translateY(-12px) scale(0.98); }
+    to { opacity: 1; transform: translateY(0) scale(1); }
 }
 
 .cp-input {