clrsrc 1.3.0

clrsrc 1.3.0

A search-quality and endgame/mate-correctness release. The embedded NNUE is
unchanged from 1.2.0 — every gain here comes from the search side.

Changed

• Singular extensions disabled — validated as a strength gain in self-play at
  our time controls.
• Reworked mate / tablebase-win score banding (Viridithas-style geometry).
  Tablebase wins now occupy their own score band and no longer masquerade as
  forced mates; a mate N score is reported only for genuine checkmates.
• Checkmate takes priority over the 50-move draw. A mate delivered with the
  halfmove counter at exactly 100 is scored as mate instead of being given away
  as a draw.

Added

• ConvFloor (default on) — a conversion-time floor. In clearly winning,
  low-piece endgames with time banked, an anti-collapse floor keeps the engine
  calculating the conversion instead of snapping off an instant move. Time-
  management only (bench-neutral). Tunable via ConvFloor / ConvThreshold /
  ConvExtend / ConvMaxPieces / ConvMinRemaining.

Fixed

• NNUE loader guard — a network whose bucket layout does not match the
  compiled layout now yields a clear error instead of an out-of-bounds panic.
• Opening-book probe hygiene — the pool cutoff anchors on the best evaluated
  score, and an empty result returns cleanly instead of a junk fallback.

Notes

• Embedded NNUE unchanged from 1.2.0 (self-contained binary; EvalFile still
  overrides).
• Assets: clrsrc-1.3.0-windows-x86_64.exe (self-contained) +
  clrsrc_v32_seed_b.nnue (network override) + jugernaut_v4.book.