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/__init__.py

@@ -16,6 +16,7 @@ from .routes.audio_templates import router as audio_templates_router
 from .routes.value_sources import router as value_sources_router
 from .routes.automations import router as automations_router
 from .routes.scene_presets import router as scene_presets_router
+from .routes.webhooks import router as webhooks_router
 
 router = APIRouter()
 router.include_router(system_router)
@@ -32,5 +33,6 @@ router.include_router(value_sources_router)
 router.include_router(picture_targets_router)
 router.include_router(automations_router)
 router.include_router(scene_presets_router)
+router.include_router(webhooks_router)
 
 __all__ = ["router"]