Contract 6.35.0

The player tools, after the Elixir Gym's second run on them (feedback #171-#172).

• fit_for on battles_meta_decks and battles_meta_cards carries recent_mean_level, the level the player fields now (their last ten decided battles, as players_collection serves it). vs_fielded and the upgrade targets read against it, and a note says when the player is levelling up. The 30-day mean alone had told a levelling account to upgrade to where it already plays (#171).
• players_summary declares both trophy_ranges and says how they differ: trophy_floor.trophy_range is trophies landed on after each ladder battle, and a deck's is the trophies its battles started at. best_deck is declared with top_deck's properties, and last_played_at is declared (#172). The values are unchanged.

Additive fields and descriptions; the upgrade target moves to the recent level.