fix(workflow): read task query variables from 'variables', not 'processVariables' (refs #13)

Flowable's POST query/tasks returns the included process variables under the key
'variables' (the request opts in via includeProcessVariables). The client DTO, its
unit test, and the live-check parser all looked for 'processVariables', so the
werkbak never matched a task's registrationId and verify-domain timed out. Verified
by driving a real Flowable instance end-to-end locally: start -> complete external
job -> the Beoordelen task carries registrationId under 'variables'.

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

infra/run-domain-check.sh

@@ -87,8 +87,9 @@ try:
 except Exception:
     d={}
 rid=os.environ['REG_ID']
+# Flowable's task-query returns the included process variables under 'variables'.
 print(next((t['id'] for t in (d.get('data') or [])
-    if any(v.get('name')=='registrationId' and v.get('value')==rid for v in (t.get('processVariables') or []))), ''))"; }
+    if any(v.get('name')=='registrationId' and v.get('value')==rid for v in (t.get('variables') or []))), ''))"; }
 
 flcurl() { docker run --rm --network "$net" curlimages/curl:latest -fsS -u rest-admin:test "$@"; }
 query='{"processDefinitionKey":"registratie","taskDefinitionKey":"Beoordelen","includeProcessVariables":true}'