fix: move large scratch buffers off stack

[xsscx]

PR Summary

#1715

Checklist

• [y] Signed all Commits in PR
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• [y] Ran sanitizer coverage for memory-safety or parser changes
• [y] Added or updated regression coverage for behavior changes
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• [y] Did not change maintainer-owned workflow, CTest, CPack, sanitizer, release, or security infrastructure unless requested by an iccDEV maintainer
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• Code style matches nearby code: 2-space indent, K&R braces, m_ members

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[Copilot]

Pull request overview

Moves oversized scratch buffers from stack to heap to prevent WebAssembly stack overflows reported in #1715.

Changes:

• Replaces large automatic buffers with vectors.
• Preserves existing zlib and CLUT behavior.
• Adds a WASM CLUT dump regression test.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
IccProfLib/IccTagLut.cpp	Heap-allocates the 200 KB CLUT dump buffer.
IccProfLib/IccTagBasic.cpp	Heap-allocates four 32 KB zlib buffers.
Build/Cmake/wasm-package/test_all.js	Exercises CLUT profile dumping under WASM.