[KnightStackSys]

Summary

• Replace outdated/closed PR Add team-wide complementary bishop-pair evaluation #44 using fresh main.
• Reward one complementary bishop-pair bonus per 4PC team, including a light-squared bishop owned by one teammate and a dark-squared bishop owned by the partner; no bonus if the team has bishops of only one square color.
• Exclude eliminated partners and avoid multiplying the bonus when extra bishops exist.
• Optimize evaluation hot path: precompute the two square-color Bitboard masks once during Geometry::init(); intersect the live team's bishop bitboards instead of scanning each bishop and computing file/rank parity during every static evaluation.
• Lower default from 40 to 10 centipawns following an observed ~−40 Elo strength test with the 40 cp implementation.
• Keep UCI EvalBishopPairBonus tunable from 0 (disabled) to 1000. ResetTuning restores 10.
• Preserve material, mobility, attacked-piece evaluation, and NNUE behavior; add CTest assertions for the bitboard masks and pair rules.

Validation

Linux GCC CI passed. Windows MSVC CI in progress. No controlled NPS benchmark or repeat SPRT yet; speed and strength gains are not assumed.