Enable OpenMP threading in finite-difference kernels (diff_new, diff_new_sh, diff_newwb,
lopsidediff, kodiss, kodiss_sh) with collapse(3) directives on 36 triple-nested loops.
Update build flags (-qopenmp), MPI process binding, and runtime configuration.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>