spconv KRSC [O,kz,ky,kx,I] and torch Conv3d [O,I,kz,ky,kx] are both rank 5 and cannot
be separated by rank. Both LATO.2 and Pixal3D contain a mix, and guessing wrong is
silent - the reshape succeeds and the output is quietly garbage. Verified against
Pixal3D's real weights: ss_dec classified conv3d (20), shape_dec/tex_dec krsc (40 each).
