put_u8/16/32/64 and get_u8/16/32/64 (plus signed variants) for packing and unpacking values at explicit byte offsets in a buffer. Each value is encoded byte-by-byte with explicit shift operations — no struct casting, no alignment assumptions, correct on any host endianness. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>