lamfold-cramfs — third-party attribution

lamfold-cramfs is original Lamco Development work (MIT OR Apache-2.0),
clean-roomed from the public cramfs format:

  cramfs (Compressed ROM filesystem) on-disk format
      — kernel Documentation/filesystems/cramfs.rst + cramfs_fs.h
      (superblock, 12-byte bitfield inode, directory records, the per-page
       zlib block index)

The following GPL implementation was explicitly FENCED OFF — not read, not
transcribed:

  Linux kernel fs/cramfs   GPL-2.0

There was nothing permissive to reuse: the `cramfs` crate on crates.io is
unbuildable upstream, so this is from-scratch. Compression is delegated to the
lamfold substrate codec (`Codec::Zlib`, miniz_oxide — permissive); this crate
contains no compression code.

Test fixtures are generated with mkcramfs from cramfs-tools (a tool, not a
source) and verified with cramfsck as an oracle; the on-disk bytes are data, not
code.

M0 license-gate audit: the project license audit
