feat: HA light output targets — cast LED colors to Home Assistant lights

New output target type `ha_light` that sends averaged LED colors to HA
light entities via WebSocket service calls (light.turn_on/turn_off):

Backend:
- HARuntime.call_service(): fire-and-forget WS service calls
- HALightOutputTarget: data model with light mappings, update rate, transition
- HALightTargetProcessor: processing loop with delta detection, rate limiting
- ProcessorManager.add_ha_light_target(): registration
- API schemas/routes updated for ha_light target type

Frontend:
- HA Light Targets section in Targets tab tree nav
- Modal editor: HA source picker, CSS source picker, light entity mappings
- Target cards with start/stop/clone/edit actions
- i18n keys for all new UI strings

server/src/wled_controller/static/locales/en.json

@@ -759,6 +759,9 @@
     "dashboard.perf.gpu": "GPU",
     "dashboard.perf.unavailable": "unavailable",
     "dashboard.perf.color": "Chart color",
+    "dashboard.perf.mode.system": "System",
+    "dashboard.perf.mode.app": "App",
+    "dashboard.perf.mode.both": "Both",
     "dashboard.poll_interval": "Refresh interval",
     "automations.title": "Automations",
     "automations.empty": "No automations configured. Create one to automate scene activation.",
@@ -1815,6 +1818,31 @@
     "ha_source.deleted": "Home Assistant source deleted",
     "ha_source.delete.confirm": "Delete this Home Assistant connection?",
     "section.empty.ha_sources": "No Home Assistant sources yet. Click + to add one.",
+    "ha_light.section.title": "HA Lights",
+    "ha_light.section.targets": "HA Light Targets",
+    "ha_light.add": "Add HA Light Target",
+    "ha_light.edit": "Edit HA Light Target",
+    "ha_light.name": "Name:",
+    "ha_light.name.placeholder": "Living Room Lights",
+    "ha_light.ha_source": "HA Connection:",
+    "ha_light.css_source": "Color Strip Source:",
+    "ha_light.update_rate": "Update Rate:",
+    "ha_light.update_rate.hint": "How often to send color updates to HA lights (0.5-5.0 Hz). Lower values are safer for HA performance.",
+    "ha_light.transition": "Transition:",
+    "ha_light.transition.hint": "Smooth fade duration between colors (HA transition parameter).",
+    "ha_light.mappings": "Light Mappings:",
+    "ha_light.mappings.hint": "Map LED ranges to HA light entities. Each mapping averages the LED segment to a single color.",
+    "ha_light.mappings.add": "Add Mapping",
+    "ha_light.mapping.entity_id": "Entity ID:",
+    "ha_light.mapping.led_start": "LED Start:",
+    "ha_light.mapping.led_end": "LED End (-1=last):",
+    "ha_light.mapping.brightness": "Brightness Scale:",
+    "ha_light.description": "Description (optional):",
+    "ha_light.error.name_required": "Name is required",
+    "ha_light.error.ha_source_required": "HA connection is required",
+    "ha_light.created": "HA light target created",
+    "ha_light.updated": "HA light target updated",
+    "section.empty.ha_light_targets": "No HA light targets yet. Click + to add one.",
     "automations.condition.home_assistant": "Home Assistant",
     "automations.condition.home_assistant.desc": "HA entity state",
     "automations.condition.home_assistant.ha_source": "HA Source:",