Add visual display layout and enhanced display information in Web UI

- Visual display layout visualization showing all monitors in their relative positions
- Displays are scaled proportionally and positioned based on actual coordinates
- Primary displays marked with star icon and green borders
- Secondary displays with gray borders
- Hover effects on display visualization with detailed tooltips
- Color-coded legend explaining primary/secondary displays
- Enhanced display cards with primary/secondary badges
- Added display index to display cards for clarity
- Added lightbulb emoji favicon for browser tab

This makes it much easier to understand multi-monitor setups and identify
which physical monitor corresponds to which display index when configuring
WLED devices.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

server/src/wled_controller/static/style.css

@@ -223,14 +223,151 @@ section {
     border: 1px solid var(--border-color);
     border-radius: 8px;
     padding: 15px;
-    text-align: center;
+}
+
+.display-header {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    margin-bottom: 15px;
 }
 
 .display-index {
-    font-size: 2rem;
+    font-size: 1.3rem;
     font-weight: 700;
     color: var(--info-color);
-    margin-bottom: 10px;
+}
+
+.badge-primary {
+    background: var(--primary-color);
+    color: white;
+}
+
+.badge-secondary {
+    background: var(--border-color);
+    color: var(--text-secondary);
+}
+
+/* Display Layout Visualization */
+.display-layout-preview {
+    background: var(--card-bg);
+    border: 1px solid var(--border-color);
+    border-radius: 8px;
+    padding: 20px;
+    margin-bottom: 20px;
+}
+
+.display-layout-preview h3 {
+    margin: 0 0 15px 0;
+    font-size: 1.1rem;
+    color: var(--text-color);
+}
+
+.display-layout-canvas {
+    background: var(--bg-color);
+    border: 2px dashed var(--border-color);
+    border-radius: 8px;
+    padding: 30px;
+    min-height: 300px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+}
+
+.layout-container {
+    position: relative;
+    background: transparent;
+}
+
+.layout-display {
+    position: absolute;
+    border: 3px solid;
+    border-radius: 8px;
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    justify-content: center;
+    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.2);
+    transition: transform 0.2s, box-shadow 0.2s;
+    cursor: help;
+}
+
+.layout-display:hover {
+    transform: scale(1.05);
+    box-shadow: 0 6px 12px rgba(0, 0, 0, 0.3);
+    z-index: 10;
+}
+
+.layout-display.primary {
+    border-color: var(--primary-color);
+    background: linear-gradient(135deg, rgba(76, 175, 80, 0.15), rgba(76, 175, 80, 0.05));
+}
+
+.layout-display.secondary {
+    border-color: var(--border-color);
+    background: linear-gradient(135deg, rgba(128, 128, 128, 0.1), rgba(128, 128, 128, 0.05));
+}
+
+.layout-display-label {
+    text-align: center;
+    padding: 5px;
+    display: flex;
+    flex-direction: column;
+    gap: 2px;
+}
+
+.layout-display-label strong {
+    font-size: 0.9rem;
+    color: var(--text-color);
+    font-weight: 600;
+}
+
+.layout-display-label small {
+    font-size: 0.75rem;
+    color: var(--text-secondary);
+}
+
+.primary-indicator {
+    position: absolute;
+    top: 5px;
+    right: 5px;
+    color: var(--primary-color);
+    font-size: 1.2rem;
+    text-shadow: 0 0 3px rgba(0, 0, 0, 0.3);
+}
+
+.layout-legend {
+    display: flex;
+    gap: 20px;
+    justify-content: center;
+    margin-top: 15px;
+    padding-top: 15px;
+    border-top: 1px solid var(--border-color);
+}
+
+.legend-item {
+    display: flex;
+    align-items: center;
+    gap: 8px;
+    font-size: 0.9rem;
+    color: var(--text-secondary);
+}
+
+.legend-dot {
+    width: 16px;
+    height: 16px;
+    border-radius: 3px;
+    border: 2px solid;
+}
+
+.legend-dot.primary {
+    border-color: var(--primary-color);
+    background: rgba(76, 175, 80, 0.2);
+}
+
+.legend-dot.secondary {
+    border-color: var(--border-color);
+    background: rgba(128, 128, 128, 0.2);
 }
 
 .add-device-section {