feat: HA light target live color preview — per-entity swatches via WebSocket

- Cache per-entity colors in HALightTargetProcessor._update_lights()
- Broadcast colors_update to WS clients at target's update_rate
- WS endpoint: /api/v1/output-targets/{target_id}/ha-light/ws
- Frontend: connect WS when target runs, update swatch colors live
- Card shows colored boxes per mapped entity with entity name labels

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

@@ -1553,6 +1553,35 @@
     height: 16px;
 }
 
+/* HA Light color swatches */
+.ha-light-swatches {
+    display: flex;
+    flex-wrap: wrap;
+    gap: 6px;
+    margin-top: 8px;
+}
+.ha-light-swatch {
+    display: inline-flex;
+    align-items: center;
+    gap: 5px;
+    padding: 3px 8px;
+    border-radius: 4px;
+    background: var(--bg-color);
+    border: 1px solid var(--border-color);
+    font-size: 0.75rem;
+}
+.ha-light-swatch .swatch-color {
+    display: inline-block;
+    width: 16px;
+    height: 16px;
+    border-radius: 3px;
+    border: 1px solid rgba(255,255,255,0.2);
+    transition: background 0.3s;
+}
+.ha-light-swatch .swatch-label {
+    opacity: 0.8;
+}
+
 .btn-remove-mapping:hover {
     opacity: 1;
 }