Add Rz Coin utility store

ENVIRONMENTS.md

@@ -77,6 +77,23 @@ Promotion is idempotent and does not delete or implicitly unpublish PRD content.
 
 ## Verification and rollback
 
+## Rz Coin Store attempt-cycle migration
+
+The QBank reset preserves every attempt and increments a user's eligibility cycle. After deploying
+the store-capable API to an environment, inspect and then apply the one-time index migration before
+using QBank reset tokens:
+
+```bash
+kubectl exec deployment/step3-api -n step3-uat -- \
+  dotnet QuestionsApi.dll migrate-question-attempt-cycles
+kubectl exec deployment/step3-api -n step3-uat -- \
+  dotnet QuestionsApi.dll migrate-question-attempt-cycles --apply --confirm MIGRATE_ATTEMPT_CYCLES
+```
+
+Repeat with namespace `step3-prd` after the tested revision is promoted to `production`. The dry run
+reports missing cycle fields and both index states. Apply backfills existing attempts to cycle zero,
+creates the three-field unique index, and only then removes the legacy two-field unique index.
+
 Check both internal and public readiness after every rollout:
 
 ```bash