[S4.1-12] Stage 4.1 Staging Cut and Rollback Drill

[humanauction]

Labels: stage-4, ops, release
Depends on: S4.1-02, S4.1-07, S4.1-10, S4.1-11

Acceptance Criteria:

• Staging deployment succeeds with latest migrations.
• Smoke test checklist passes for auth, game, stats, and admin paths.
• Rollback steps are documented and executed once in staging.
• Stage 4.1 release notes are published.