Add webhook trigger condition for automations

Per-automation webhook URL with auto-generated 128-bit hex token.
External services (Home Assistant, IFTTT, curl) can POST to
/api/v1/webhooks/{token} with {"action": "activate"|"deactivate"}
to control automation state — no API key required (token is auth).

Backend: WebhookCondition model, engine state tracking with
immediate evaluation, webhook endpoint, schema/route updates.
Frontend: webhook option in condition editor, URL display with
copy button, card badge, i18n for en/ru/zh.

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

server/src/wled_controller/core/automations/automation_engine.py

@@ -15,6 +15,7 @@ from wled_controller.storage.automation import (
     MQTTCondition,
     SystemIdleCondition,
     TimeOfDayCondition,
+    WebhookCondition,
 )
 from wled_controller.storage.automation_store import AutomationStore
 from wled_controller.storage.scene_preset import ScenePreset
@@ -55,6 +56,8 @@ class AutomationEngine:
         # automation_id → datetime of last activation / deactivation
         self._last_activated: Dict[str, datetime] = {}
         self._last_deactivated: Dict[str, datetime] = {}
+        # webhook_token → bool (volatile state set by webhook calls)
+        self._webhook_states: Dict[str, bool] = {}
 
     async def start(self) -> None:
         if self._task is not None:
@@ -213,6 +216,8 @@ class AutomationEngine:
             return self._evaluate_display_state(condition, display_state)
         if isinstance(condition, MQTTCondition):
             return self._evaluate_mqtt(condition)
+        if isinstance(condition, WebhookCondition):
+            return self._webhook_states.get(condition.token, False)
         return False
 
     @staticmethod
@@ -420,6 +425,15 @@ class AutomationEngine:
         except Exception as e:
             logger.error(f"Immediate automation evaluation error: {e}", exc_info=True)
 
+    async def set_webhook_state(self, token: str, active: bool) -> None:
+        """Set webhook condition state and trigger immediate evaluation."""
+        self._webhook_states[token] = active
+        await self.trigger_evaluate()
+
+    def get_webhook_state(self, token: str) -> bool:
+        """Read current webhook state (False if never called)."""
+        return self._webhook_states.get(token, False)
+
     async def deactivate_if_active(self, automation_id: str) -> None:
         """Deactivate an automation immediately (used when disabling/deleting)."""
         if automation_id in self._active_automations: