feat(mise): support pnpm idiomatic version files (#678)

* docs: add instructions for exploring mise internals in CLAUDE.md

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* feat(mise): add pnpm to idiomatic version file tools

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* docs(node): document pnpm version selection via devEngines

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* docs: clarify test instructions in pull request template

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* wip

* docs: remove outdated markdown line length convention

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* refactor(node): clarify pnpm version resolution rationale in comment

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* docs: add PR description warning to CLAUDE.md

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* test(generate): update snapshot to include pnpm in enabled tools

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* test(node): add test for mise idiomatic version override with pnpm

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* docs(node): document version resolution order and Mise parsing

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* test(node): add devEngines pnpm detection example

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* docs(node): document mise idiomatic package manager detection

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* feat(node): detect package manager from mise idiomatic version sources

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* test: add snapshot for node pnpm dev engines build plan

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* test: update node-pnpm-dev-engines build plan snapshot

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