Add cursor-tracking card glare and accent-linked background blobs

- Subtle radial glare follows cursor over card/template-card elements
  using a single document-level mousemove listener (event delegation)
- Ambient background blob colors now derive from the selected accent
  color with hue-shifted variants
- Glare intensity kept very subtle (3.5% dark / 12% light theme)

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

server/src/wled_controller/templates/index.html

@@ -289,6 +289,21 @@
             return L > 0.36 ? '#1a1a1a' : '#ffffff';
         }
 
+        function updateBgAnimColors(hex) {
+            const r = parseInt(hex.slice(1,3),16);
+            const g = parseInt(hex.slice(3,5),16);
+            const b = parseInt(hex.slice(5,7),16);
+            const root = document.documentElement;
+            const isDark = root.getAttribute('data-theme') !== 'light';
+            const a = isDark ? 0.12 : 0.10;
+            // Blob A: accent color
+            root.style.setProperty('--bg-anim-a', `rgba(${r},${g},${b},${a})`);
+            // Blob B: hue-shifted ~120° toward blue (swap channels)
+            root.style.setProperty('--bg-anim-b', `rgba(${b},${r},${g},${a * 0.8})`);
+            // Blob C: hue-shifted ~240° toward magenta
+            root.style.setProperty('--bg-anim-c', `rgba(${g},${b},${r},${a * 0.7})`);
+        }
+
         function applyAccentColor(hex, silent) {
             const root = document.documentElement;
             root.style.setProperty('--primary-color', hex);
@@ -296,6 +311,7 @@
             root.style.setProperty('--primary-text-color', adjustLightness(hex, theme === 'dark' ? 15 : -15));
             root.style.setProperty('--primary-hover', adjustLightness(hex, 8));
             root.style.setProperty('--primary-contrast', contrastColor(hex));
+            updateBgAnimColors(hex);
             const swatch = document.getElementById('cp-swatch-accent');
             if (swatch) swatch.style.background = hex;
             const native = document.getElementById('cp-native-accent');
@@ -332,6 +348,7 @@
 
         const savedAccent = localStorage.getItem('accentColor');
         if (savedAccent) applyAccentColor(savedAccent, true);
+        updateBgAnimColors(savedAccent || '#4CAF50');
 
         // Initialize auth state
         function updateAuthUI() {