chore: migrate from Yarn to pnpm

[electroluxcode]

Summary

This PR migrates the Plate monorepo from Yarn to pnpm for improved compatibility and performance.

Key Changes

• Package Manager Migration: Replaced Yarn 4.6.0 with pnpm 10.23.0
• Configuration Files:
  • Removed .yarnrc.yml, .yarn/ directory, and yarn.lock
  • Added pnpm-workspace.yaml and pnpm-lock.yaml
  • Created .npmrc with node-linker=hoisted to resolve TypeScript declaration file issues
• Scripts Updated: All yarn commands replaced with pnpm across:
  • Root and package-level package.json files
  • GitHub Actions workflows
  • Documentation and contributing guides
• CI/CD Updates: Updated all GitHub workflows to use pnpm/action-setup@v4
• Dependencies: Added missing peer dependencies (slate, scroll-into-view-if-needed)

Why pnpm?

• Next.js Turbopack Compatibility: Better support for Next.js 15+ with Turbopack
• Faster Installation: Improved package installation performance
• Disk Space Efficiency: Content-addressable storage saves disk space
• Stricter Dependency Resolution: Prevents phantom dependencies

Breaking Changes

None - the migration is transparent to package consumers.

Test Plan

• Install dependencies: pnpm install
• Build all packages: pnpm build
• Run tests: pnpm test
• Run lint: pnpm lint
• Verify CI/CD workflows pass
• Test local development workflow

Local verification: Lint, test, and build have been run locally and all pass.

Migration Notes

Known issue (to be fixed in a follow-up PR): The project's test setup has a circular dependency that was previously hidden by Yarn's phantom dependencies. With pnpm's stricter dependency resolution, this may surface. A separate PR will address this.

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Latest commit: 2bd0f49

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
plate	Ignored		Feb 26, 2026 6:27am

[zbeyens]

Awesome, let me know when it's ready

[zbeyens]

@electroluxcode could you give me the new value for those fields?

[electroluxcode]

@zbeyens

I tried it on Vercel, mainly using the default configuration for Next deployment, except that I changed the deployment directory to app/www. deployment address is at https://plate-www-sepia.vercel.app/

[zbeyens]

Awesome. Reach out if you have interest into being a co-maintainer / have initiatives going forward.

[zbeyens]

All good. We could even go back to the default build settings without memory overflow. Thanks again!