Add activity-core-issue-sink routing playbook and catalog entry

Agents can discover the activity-core → issue-core emission contract via
`warden route show activity-core-issue-sink` instead of messaging ops-warden
for ISSUE_CORE_API_KEY. The playbook points at owner-repo docs per the
no-double-source rule.

registry/routing/catalog.yaml

@@ -103,6 +103,17 @@ entries:
     reviewed: "2026-06-18"
     status: active
 
+  - id: activity-core-issue-sink
+    title: activity-core IssueSink → issue-core REST emission
+    need_keywords: [activity-core, issue-sink, issue-core, emission, issue_core_url, issue_core_api_key, tasks, ingest, rest, issuesink]
+    owner_repo: activity-core
+    subsystem: activity-core + issue-core
+    warden_executes: false
+    wiki_ref: wiki/playbooks/activity-core-issue-sink.md#worker-checklist
+    canon_ref: net-kingdom/docs/platform-identity-security-architecture.md
+    reviewed: "2026-06-18"
+    status: active
+
   # --- draft: owner path not yet shipped; hidden from default lookup ---
   - id: issue-core-ingestion-api-key
     title: issue-core ingestion API key (OpenBao path TBD)