docs: merge TESTING.md into CONTRIBUTING.md, remove TESTING.md#2228

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mnriem merged 2 commits intogithub:mainfrom

mnriem:fix/merge-testing-into-contributing-2226

Apr 15, 2026

Commits on Apr 15, 2026

docs: merge TESTING.md into CONTRIBUTING.md, remove TESTING.md
mnriem
committed
docs: address review — narrow automated checks intro, use cross-platform temp path
mnriem
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