New CuasRTUtils.showConvKernel5d(data, roi, titles, title): renders the
vout_dim×vout_dim velocity map for each ROI pixel as a tiled flat image,
with a 1-px NaN separator grid between pixel blocks (visible in ImageJ).
Sub-pixels (pixel_decimate>1) tile within each block.

CuasDetectRT: add curt_save_c5rect save calls at level-0 and each pyramid
level (title suffix "-RECT", "-LEVn-RECT"). curt_save_c5full path unchanged.
Co-authored-by: Claude <claude@elphel.com>