Support LZMA (method 14) compression in zip archives

[jonnyyu]

Summary

Enable the lzma feature of the zip crate so that zip archives with LZMA-compressed entries (zip compression method 14) can be unpacked. Before this change, such archives failed with compression method not supported: 14.

• Cargo.toml: add lzma to the zip features. This adds the pure-Rust lzma-rust2 dependency.
• src/util/unarchive.rs: add a unit test that unpacks src/util/testdata/lzma.zip. The file was created with 7z a -tzip -mm=LZMA. The test fails without the lzma feature.
• dotslash-file.md: document the zip compression methods that are supported (store, deflate, LZMA).

Test plan

• cargo test passes.
• cargo clippy shows no new warnings compared to main.
• cargo build --release succeeds.
• Manually verified on Windows: a DotSlash file with "format": "zip" that points to an LZMA zip built with 7-Zip fails on main and runs with this change.

🤖 Generated with Claude Code

[meta-codesync]

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