Registers the type id, file type and block size, and implements numpy
dequantization (verified bit-exact against the C implementation with
gguf-py/tests/test_quants.py, including random byte payloads).
Quantization is intentionally left unimplemented, like the K-quants:
DT3 planes come from an external solver (PTQTP) and are packed
directly, so a from-float numpy path would only invite quantizing
models with the wrong algorithm.
Millaguie
985b0ecba2