advanceNBAPlayInWinner was writing the PIR1 7v8 winner to participant1Id
of First Round M3/M7, but those slots already hold E2/W2 (seeded at
generation time). The "already filled" guard fired, silently swallowing
both the winner advancement and the loser's placement into Play-In
Round 2 — so the 7/8 loser never appeared in the second play-in game.
Fix: write the 7v8 winner to participant2Id (the correct null slot) and
update the guard, doc comment, and load-bearing comment accordingly.
Also swap the p2Override arguments in the simulator and test fixture to
match the corrected slot layout (FR M3: E2=p1, E7=p2).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
346121b397