ggml_validate_row_data now rejects unreachable code bytes: the ceiling
division packing reaches only 243 of the 256 byte values in qs and 81
in qh (4 trits plus an always-zero padding digit), so corruption that
previously loaded and generated garbage silently is caught at load
time. Previously only the two fp16 scales were checked.
quantize_dt3 no longer discards quant_weights silently: an ignored
imatrix now prints a loud warning (once), otherwise an imatrix A/B on
DT3 would come out byte-identical and invite the false conclusion that
the imatrix does nothing.
The two initial trit passes of quantize_row_dt3_ref now clamp like the
refit passes do, so a NaN input cannot push an out-of-range value from
lroundf into the packer.