Three small fixes from secondary code review:
1. configNumber: allow value >= 0 (not just > 0) so admins can
legitimately set baseDrawRate or drawDecay to 0 without the value
being silently discarded and replaced with the default.
2. Add logger.warn when a participant is excluded from simulation due
to a missing Elo rating, matching the NLL bracket-aware pattern.
Gives admins a visible signal instead of a silent exclusion.
3. getBySeeds: build a Map once instead of calling Array.find() per
seed. Eliminates 4M linear scans across 50k iterations for a 9-
element array — trivially fast either way, but Map is the right tool.
https://claude.ai/code/session_015wkBJ3SYGcMGjsddKKGkwa
8a0103e4c4