execImcltRbgAll(ref_scene) was dropped on the JNA side: native imclt was
hardcoded to gpu_clt, so rendering the reference scene actually rendered the
scene. Add a use_ref arg -> select gpu_clt_ref. Needed so the reference-CLT
post-mortem render reflects the real buffer (CORR2D-all-NaN divergence: inter
correlation needs BOTH gpu_clt + gpu_clt_ref; gpu_clt proven good via SOURCE).
Updated the internal selftest caller to (p,1,0).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>