Plan §3.7.1 specifies 20% spawn radius for 2-player (~4 tiles from center,
~8 tiles apart). Code had 25% (~5 tiles from center, ~10 tiles apart), which
placed bots outside the 6-tile attack radius, preventing combat engagement.
With 20% radius (4 tiles from center, 8 tiles apart), bots are within attack
range after one move and consistently engage in combat. Test replays show
combat_death events in all seeds, with 0 zone_death events.
Also adjusted secondaryRadius to 0.25 (from 0.20) to ensure secondary cores
spawn outside zone_min_radius=3, fixing TestSpawnRadiusOutsideZone for
2-player-2-cores case.
Closes: bf-by1l
826746d101