Break leaderboard ties with Melee's tiebreakers

After total of all sessions, ties fall to OMW%, GW% and OGW% over all the
league's matches (bye = 2-0 win, not an opponent; opponents floored at 1/3),
then name. Verified identical to Melee's order and percentages on a real
night. The leaderboard shows the three percentages.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CLAUDE.md

@@ -19,7 +19,9 @@ add `ALTER TABLE ... IF NOT EXISTS` statements to `init` or introduce a migratio
 
 ## Rules and decisions
 - Scoring: match win 3, draw 1, loss 0, bye = 2-0 win. Session score = sum of that night's match points.
-  Leaderboard = sum of each player's best `league.best_n` session scores; tiebreak = total of all sessions, then name.
+  Leaderboard = sum of each player's best `league.best_n` session scores; tiebreak = total of all sessions, then Melee's
+  tiebreakers (OMW%, GW%, OGW% over all the league's match rows; bye = 2-0 win, not an opponent; opponents floored at 1/3;
+  verified identical to Melee on a real night), then name. Standings-only sessions add nothing to the tiebreakers.
 - A session with match rows is scored from them; otherwise from imported standings (`session_results`).
   Standings imports have W-D-L but no opponents, so the leaderboard shows "–" W-D-L for players with such a session.
 - Players are identified by real name (Melee `Team.Players[0].Name`, falling back to DisplayName, then Username),