feat(workers): enroll webhook worker in the Workers panel registry

Add "webhook" to KNOWN_WORKERS + the start-all preferred order so the
Config → Workers panel picks up the row automatically: heartbeat
subscription, start/stop controls via the existing systemd helper
(decnet-webhook.service.j2 already lands via decnet init's unit
glob), and the status-dot lifecycle all come for free.

Placed between mutator and the swarm-only agent/forwarder/updater
trio — matches the intended startup sequence (bus → api → data-plane
workers → egress → swarm management).

No frontend change needed; Config.tsx reads the worker list
dynamically from GET /api/v1/workers.

decnet/web/router/workers/api_start_all_workers.py

@@ -25,6 +25,7 @@ _PREFERRED_ORDER: tuple[str, ...] = (
     "sniffer",
     "prober",
     "mutator",
+    "webhook",
 )
 
 

decnet/web/worker_registry.py

@@ -38,6 +38,7 @@ KNOWN_WORKERS: tuple[str, ...] = (
     "sniffer",
     "prober",
     "mutator",
+    "webhook",    # external SIEM/SOAR egress — bus consumer → HMAC HTTP POSTs
     "agent",
     "forwarder",
     "updater",