Everything else the API forgets about a season

Every Path of Legends season's final standing since S97 — the settled board at full depth, 9,999 places — is now in the record, backfilled, and each new season's final is fetched the day after it rolls. The clan ladders (clan score, clan war trophies) are recorded daily for global, the US and Japan; the game-mode leaderboards (Merge Tactics, Touchdown, 2v2 League…) are enumerated from the API so a rotating board is followed, never named; and the events the game lists as running are recorded daily as sightings, since the API gives no dates, so the season has a calendar. Three new tools read it — rankings_clan_ladder, rankings_timeline (a player's rank at every snapshot, a clan's, or the board's own floor and summit), game_events — and rankings_players takes board pol_final with a season, or board mode with a leaderboard id. Contract 1.4.0. Also fixed: since last night's deploy every board was being re-planned every fifteen minutes as never-fetched — about 1,500 extra fetches an hour — because admission stamped the board's freshness under the wrong key.