Stability checkpoint — iris-common SHA bump (ADR-0066/0067/0068)

- chore(submodule): bump iris-common SHA -> 47484f4 (picks up ADR-0066 auto-merge + 0067 redpanda + 0068 SaaS routing)

- ✅ Main pipeline #2514218901 success
- ✅ Integration-tests on SaaS Linux runner pass
- ✅ Auto-merge dev → main fires correctly