Persist required approval policy and sandbox mode for sessions

- Make `approvalPolicy` and `sandboxMode` required in orchestration contracts and turn-start flow
- Add defaults in provider reactors/ingestion to guarantee values are always set
- Store and hydrate both fields in projection persistence, snapshots, and related tests
4d791fe27cJulius Marminge committed on 2/27/2026, 5:08:38 AMparent422160a
19 files changedLine totals unavailable