nurbs::knots::KnotVector (NL_KNOTVECTOR) with find_span, find_span_and_mult,
span_count, validate, basis_eval, basis_i_eval, basis_i_derivs and the
parameter checks; SolidError::Nlib + NlibCode for NLib error numbers.
C++ shim, ffi wrapper, difftest runner and fixtures: 1753 fixture + 1200
generated cases, all bit-identical to upstream (50k-seed run also clean).
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
bherbruck