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/storage/automation.py

@@ -30,6 +30,8 @@ class Condition:
             return DisplayStateCondition.from_dict(data)
         if ct == "mqtt":
             return MQTTCondition.from_dict(data)
+        if ct == "webhook":
+            return WebhookCondition.from_dict(data)
         raise ValueError(f"Unknown condition type: {ct}")
 
 
@@ -158,6 +160,23 @@ class MQTTCondition(Condition):
         )
 
 
+@dataclass
+class WebhookCondition(Condition):
+    """Activate via an HTTP webhook call with a secret token."""
+
+    condition_type: str = "webhook"
+    token: str = ""  # auto-generated 128-bit hex secret
+
+    def to_dict(self) -> dict:
+        d = super().to_dict()
+        d["token"] = self.token
+        return d
+
+    @classmethod
+    def from_dict(cls, data: dict) -> "WebhookCondition":
+        return cls(token=data.get("token", ""))
+
+
 @dataclass
 class Automation:
     """Automation that activates a scene preset based on conditions."""