Fixed

• A .zip whose entries use Zstandard (method 93) can now be read. Every such entry previously failed with compression method not supported: 93 while the rest of the archive extracted around it, so a real archive came out partially populated with thousands of individual errors rather than one clear refusal. Repackers have largely moved to zstd-in-zip because it is much faster than DEFLATE at a similar ratio, so this is common in the wild rather than exotic. It had never worked in any release. The exclusion was deliberate and its reason had expired: the ZIP dependency took pure-Rust features only so the default build needs no C toolchain, and that was written before Cram linked C zstd at all. It does now, and the zip crate wants the same crate at the same version, so reading method 93 rides on the existing zstd-c feature and costs the shipped binaries nothing. A default cargo install cram-cli build is unchanged and still has no C dependency, so it still cannot read these archives.