chore: migrate to pinned actions

[remyleone]

No description provided.

[Copilot]

Pull request overview

This PR updates the repository’s GitHub Actions workflows to pin commonly used third-party actions (checkout, setup-node, pnpm setup) to specific commit SHAs, improving supply-chain security and build reproducibility.

Changes:

• Pin actions/checkout to a specific commit SHA (annotated with the intended version).
• Pin actions/setup-node to a specific commit SHA (annotated with the intended version).
• Pin pnpm/action-setup to a specific commit SHA (annotated with the intended version).

Reviewed changes

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

File	Description
.github/workflows/test.yml	Pins action dependencies used across multiple test jobs to specific SHAs.
.github/workflows/lint.yml	Pins checkout/node/pnpm setup actions for the lint workflow.
.github/workflows/check-dist.yml	Pins checkout/node/pnpm setup actions for the dist verification workflow.

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