Guard provider lifecycle updates to primary thread and active turn

- Ignore auxiliary/non-active turn completions for session lifecycle and checkpoints
- Restrict runtime thread/turn IDs to provider IDs in contracts
- Add regression tests and ADR for lifecycle ownership rules
d19b2f56a8Julius Marminge committed on 2/27/2026, 6:01:26 PMparent041acf1
7 files changedLine totals unavailable