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/api/routes/webhooks.py

@@ -0,0 +1,57 @@
+"""Webhook endpoint for automation triggers.
+
+External services call POST /api/v1/webhooks/{token} with a JSON body
+containing {"action": "activate"} or {"action": "deactivate"} to control
+automations that have a webhook condition.  No API-key auth is required —
+the secret token itself authenticates the caller.
+"""
+
+from fastapi import APIRouter, Depends, HTTPException
+from pydantic import BaseModel, Field
+
+from wled_controller.api.dependencies import get_automation_engine, get_automation_store
+from wled_controller.core.automations.automation_engine import AutomationEngine
+from wled_controller.storage.automation import WebhookCondition
+from wled_controller.storage.automation_store import AutomationStore
+from wled_controller.utils import get_logger
+
+logger = get_logger(__name__)
+router = APIRouter()
+
+
+class WebhookPayload(BaseModel):
+    action: str = Field(description="'activate' or 'deactivate'")
+
+
+@router.post(
+    "/api/v1/webhooks/{token}",
+    tags=["Webhooks"],
+)
+async def handle_webhook(
+    token: str,
+    body: WebhookPayload,
+    store: AutomationStore = Depends(get_automation_store),
+    engine: AutomationEngine = Depends(get_automation_engine),
+):
+    """Receive a webhook call and set the corresponding condition state."""
+    if body.action not in ("activate", "deactivate"):
+        raise HTTPException(status_code=400, detail="action must be 'activate' or 'deactivate'")
+
+    # Find the automation that owns this token
+    for automation in store.get_all_automations():
+        for condition in automation.conditions:
+            if isinstance(condition, WebhookCondition) and condition.token == token:
+                active = body.action == "activate"
+                await engine.set_webhook_state(token, active)
+                logger.info(
+                    "Webhook %s: automation '%s' (%s) → %s",
+                    token[:8], automation.name, automation.id, body.action,
+                )
+                return {
+                    "ok": True,
+                    "automation_id": automation.id,
+                    "automation_name": automation.name,
+                    "action": body.action,
+                }
+
+    raise HTTPException(status_code=404, detail="Webhook token not found")