Refactor the Stage-2 selftest into run_convert_pipeline(do_imclt) shared helper;
tp_convert_direct_selftest is now a thin wrapper (do_imclt=0). Add tp_imclt_selftest
(do_imclt=1): after convert_direct, allocate pitched RBG output buffers (alloc_image_gpu,
648x520/cam, mono), launch imclt_rbg_all <<<1,1>>> (gpu_clt -> gpu_corr_images),
de-pitch via cudaMemcpy2D, compare to clt/aux_chnN.rbg golden.

Validated on RTX 5060 Ti via Java->JNA: max|RBG-golden|=0.0201 over peaks 1535 ->
relative ~1.31e-5. convert_direct CLT error unchanged (0.108505) => no regression.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>