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/tests/storage/test_output_target_store.py

@@ -1,4 +1,4 @@
-"""Tests for OutputTargetStore — CRUD for LED and key_colors targets."""
+"""Tests for OutputTargetStore — CRUD for LED and HA light targets."""
 
 import pytest
 
@@ -34,18 +34,6 @@ class TestOutputTargetModel:
         assert isinstance(target, WledOutputTarget)
         assert target.device_id == "dev_1"
 
-    def test_key_colors_type_rejected(self):
-        """key_colors target type removed — from_dict raises ValueError."""
-        data = {
-            "id": "pt_2",
-            "name": "KC Target",
-            "target_type": "key_colors",
-            "created_at": "2025-01-01T00:00:00+00:00",
-            "updated_at": "2025-01-01T00:00:00+00:00",
-        }
-        with pytest.raises(ValueError, match="Unknown target type"):
-            OutputTarget.from_dict(data)
-
     def test_unknown_type_raises(self):
         data = {
             "id": "pt_3",
@@ -78,11 +66,6 @@ class TestOutputTargetStoreCRUD:
         assert t.name == "LED 1"
         assert store.count() == 1
 
-    def test_create_key_colors_target_rejected(self, store):
-        """key_colors target type is no longer supported (migrated to CSS source)."""
-        with pytest.raises(ValueError, match="Invalid target type"):
-            store.create_target(name="KC 1", target_type="key_colors")
-
     def test_create_invalid_type(self, store):
         with pytest.raises(ValueError, match="Invalid target type"):
             store.create_target(name="Bad", target_type="invalid")