fix: pin fflate to 0.8.2 to work around attw tarball-read crash

[hmalik88]

Pins fflate because 0.8.3 changed Gunzip's streaming callback to emit trailing empty chunks at end-of-stream. @arethetypeswrong/core (via @andrewbranch/untar.js) captures only the last chunk, so it gets an empty buffer, returns [] from untar, and crashes with "Cannot read properties of undefined (reading 'filename')" in the Compatibility test job of #287

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Note

Low Risk
Low risk: dependency resolution-only change that pins fflate to a known-good version to stabilize the test/tooling pipeline.

Overview
Pins transitive dependency fflate to 0.8.2 using Yarn resolutions to avoid a regression that breaks attw --pack.

Updates yarn.lock to reflect the forced fflate@0.8.2 resolution (removing the ^0.8.2 range entry).

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