Make build_player_table leak-free for a past-season backtest

Passing a past season (e.g. 2025 to backtest a 2025 draft) previously still
pulled every season in the cache for production stats, O-line/pace/defense
ratings, and rookie draft-curve fitting -- all bounded by CURRENT_SEASON, not
the season being predicted. A 2025 "backtest" could see 2025's own results.

Every history-derived input is now bounded to the five seasons strictly
before `season`, matching the lookback the live board already gets by
construction (weekly_stats/play_by_play don't have a season that hasn't
happened yet). The live depth-chart team override is skipped for a past
season too, since it reflects today's rosters, not that season's -- team
now comes from that season's own box scores instead.

player_season_profiles gains an optional seasons bound to support this;
default behavior (season=CURRENT_SEASON, seasons=None) is unchanged.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>