feat: advance LOOP-WP-0002/0003/0004 without activity-core blockers

Document event payload contract, draft disabled ActivityDefinitions for
CI/regulator/registry hygiene, initialize loop health snapshots and
regulator dashboard, record DEC-005 kaizen-stack promotion, and close
supplier-independent workplan tasks.

loops/registry-hygiene/round-robin-state.json

@@ -0,0 +1,6 @@
+{
+  "cursor_domain": "custodian",
+  "cursor_index": 0,
+  "last_run": null,
+  "last_batch": []
+}