fix(auth): make session-affinity updates safe for rebound sessions

- Propagate session-affinity provider/model metadata through selection and execution results so affinity cleanup uses the same namespace/model keys as selection.
- Forward execution `Options` in `Result` across normal, home, and stream paths, then hook manager cooldown handling to notify the affinity selector.
- Add `Touch`/`CompareAndDelete` to session cache and switch affinity release logic to compare-and-delete semantics, preventing stale failures from deleting a session already rebound to another auth.

Closes: #4989