SessionConfig

Session semantics: a session ends when the app has been inactive for longer than backgroundTimeout. Session state is persisted, so a session survives process restarts as long as activity resumes within the timeout.

This shape is frozen. A data class constructor cannot gain a parameter without breaking ABI, so further session knobs go on AutographConfig as properties rather than here — see ../../../../../../../docs/adr/0001-public-api-evolution.md §2b.