* feat(artifacts): read UnityFS AssetBundle containers

inspect-artifact and extract-artifact now recognize the UnityFS signature
and treat format versions 6 through 9 as containers. Header facts (format
version, player/engine strings, declared size, dataflags, blocks-info
bounds and the declared 16-byte data hash) are retained alongside a
directory of CAB-* and .resS members. Member bytes stream on demand:
only the blocks covering the requested member are read and decompressed
with bounded expansion and cancellation.

Bundles declaring asset-bundle encryption keep header facts and report
unknown directory coverage. LZMA blocks-info reports unknown coverage;
LZMA member reads fail as unavailable while the directory stays
readable. Malformed counts, out-of-stream members and declared sizes
beyond the file fail as format errors. UnityFS classifies by bytes in
root detection, inventory graph construction and desktop inspection,
which emits a unityfs-header fact.

Validation: tsc --noEmit, oxlint (no new findings on touched files),
17 reader tests covering LZ4HC/uncompressed tables, blocks-info at end,
format 6 without padding alignment, multi-block members, malformed
input, unsupported compression, cancellation and abandoned streams;
full artifacts/domain/conformance suites pass. Verified against one
real YooAsset bundle (Unity 2021.3.32f1, format 8, LZ4HC): the
streamed SerializedFile contained its managed assembly byte-identical
to a UnityPy extraction. Other producer variants unverified.

* fix(unityfs): own bounded member reads and preserve partial evidence

* refactor(unityfs): clarify producer revision flag decisions

* fix(artifacts): preserve coverage authority and bound UnityFS block work

---------

Co-authored-by: gensokyo-dev <342580529+gensokyo-dev@users.noreply.github.com>