fix: rewrite extra fields

[Its-Just-Nans]

Second part of the extra fields rewrite

Big change is that ExtraFields are now structs, not random Vec<u8>

[amazon-q-developer]

This PR successfully refactors extra fields from raw byte vectors to structured types, improving type safety and maintainability. The changes correctly preserve functionality while making the codebase more robust. The refactoring includes:

• Replacing #[repr(packed, C)] with proper typed structs in AexEncryption
• Improving Zip64ExtendedInformation::parse to handle u32/u64 conversions correctly
• Adding write methods for UnicodeExtraField
• Creating a new structured ExtraField enum

No blocking issues found. The code is ready for merge once the draft status is resolved and the mentioned tests are fixed.

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[gemini-code-assist]

Code Review

This pull request refactors the handling of ZIP extra fields by replacing raw byte arrays with a structured ExtraFields type and ExtraField enum, updating both the reader and writer implementations to parse, apply, and serialize these fields directly. The review feedback highlights several critical areas for improvement: a potential infinite loop/DoS vulnerability in stream reading on Io errors, unnecessary heap allocations when skipping bytes, robustness issues when parsing invalid UTF-8 in Unicode comments or paths, and multiple uses of unstable let-chains that could break MSRV compatibility. Additionally, a breaking change was identified in ZipFile::extra_data where it returns empty vectors instead of None, and some commented-out code needs to be cleaned up.

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[Pr0methean]

I've started to review this version of the PR, and will likely be able to finish in the next few days.

[Pr0methean]

This is a partial review; it covers all except src/write.rs and tests/*.rs.