Contract 7.1.10

The card tools after the Elixir Gym's fifth run on them (feedback #281-#285).

• cards_card card.first_played keeps each form's earliest deck: on the four cards with both an Evolution and a Hero, a later row had overwritten base's date (#281).
• A tower troop passed to the card tools is refused as what it is, with where tower troops are read, instead of "not in the catalog" beside cards_catalog listing it (#282).
• cards_card members.held[].observed_at is the newest read of the member's collection; since keeps when that level was first seen, which is what it had served (#283).
• The shrinkage note says shrunk_win_rate is withheld when the POPULATION holds fewer than 30 decided observations; a row with few battles still carries one (#284).

Additive.