Contract 9.13.0

clans_participation says who was in the clan, and in what role, at each war finish (#46), so a clan's own rules can be replayed at a past finish without applying today's roster and roles to it.

• Each member row carries in_clan_at_war_finish and role_at_war_finish, aligned to war_weeks as war_decks is. Each is read from the clan's roster reads on either side of the finish and served only when the two agree; null is unknown, never absent: the week is unfinished, no read follows the finish yet, or the change fell between the reads. A role is also null outside the clan, at a finish before role_history_since (the first live roster read; imported history carries tenure, not roles), and where a member's recorded role changes do not chain, as when an older roster was admitted after a newer one.
• At full verbosity each row carries role_changes: every role change observed in the window, with role_before, role_after, window_start and observed_at.
• former_members lists who left inside the window and has not come back, with role_at_departure, the join and leave instants and the same columns; their battles and donations count only what they played and gave in this clan. former_member_count counts them.

Additive. The eight-week full read of a large clan with many departures can pass the result cap, whose refusal names weeks and verbosity: "compact"; the JSON API operation has no cap.