Reader and writer ported from filius-ipad with the same path policy, limits and error codes; DEFLATE via fflate, cut at the declared size like Apple Compression. 54 tests: the Swift archive rejection tests, DEFLATE edge cases, and all 23 corpus files cross-checked against fflate.unzipSync and round-tripped. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>