feat(infra): Flowable RegistratieVerlopen worker + document-wait completion (refs #102)

FlowableWorkflowClient implements IRegistratieVerlopenClient (acquire/complete the
RegistratieVerlopen jobs) and CompleteDocumentWaitAsync (complete WachtOpDocumenten,
best-effort). Wires the RegistratieVerlopenProcessor + hosted RegistratieVerlopenPump
into the domain host and excludes the pump from mutation (like the other pumps).
Fakes updated for the new IWorkflowClient member.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

services/domain/stryker-config.json

@@ -5,7 +5,8 @@
     "reporters": ["progress", "html"],
     "mutate": [
       "!**/OpenZaakJobPump.cs",
-      "!**/BeoordelingEscalatiePump.cs"
+      "!**/BeoordelingEscalatiePump.cs",
+      "!**/RegistratieVerlopenPump.cs"
     ],
     "thresholds": {
       "high": 95,