Add two configurable leaderboard settings per league, replacing the global
constants with per-row DB columns:
- eligible_min_sessions (default 3): minimum sessions before a player ranks
on the main leaderboard rather than showing as provisional
- break_even_cents (default 100 = $1.00): sessions within ±this of $0 net
are classified as break-even rather than a win or loss
Changes:
- Migration 0003 adds both columns with server defaults for existing leagues
- League DB model gains eligible_min_sessions and break_even_cents columns
- net_result_bucket() and build_leaderboard() accept optional tolerance param
- summarize_player_runs() passes tolerance to net_result_bucket for streaks
- League leaderboard route reads values from the league row instead of config
- League settings form exposes both fields with validation (1-100 sessions,
$0.00-$100.00 threshold)
SowinskiBraeden