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/static/locales/en.json

@@ -607,6 +607,12 @@
   "automations.condition.mqtt.match_mode.contains": "Contains",
   "automations.condition.mqtt.match_mode.regex": "Regex",
   "automations.condition.mqtt.hint": "Activate when an MQTT topic receives a matching payload",
+  "automations.condition.webhook": "Webhook",
+  "automations.condition.webhook.hint": "Activate via an HTTP call from external services (Home Assistant, IFTTT, curl, etc.)",
+  "automations.condition.webhook.url": "Webhook URL:",
+  "automations.condition.webhook.copy": "Copy",
+  "automations.condition.webhook.copied": "Copied!",
+  "automations.condition.webhook.save_first": "Save the automation first to generate a webhook URL",
   "automations.scene": "Scene:",
   "automations.scene.hint": "Scene preset to activate when conditions are met",
   "automations.scene.search_placeholder": "Search scenes...",