Contract 7.2.2

The pre-beta Gym pass, first fixes (feedback #314-#316).

• The API reports no tower troop on river race (war) battles. battles_meta_cards with tower_troops: true serves tower_troop_known_battles and takes each tower troop's usage_share over it, so a war player's shares are no longer 10-40 points low; decided_battles stays the eight-card read's number, including on mode: war, where it had read 0. cards_card on a tower troop carries the same count and note (#315).
• game_events says its first/last sighting fields are the record's whole span, bounded by gaps between reads, not the window's.

Additive.