Migrate from CJS to ESM

[mizdra]

• require(esm) is available in Node.js v20.19.0
  • https://nodejs.org/api/modules.html#loading-ecmascript-modules-using-require
• In the desktop version of VS Code, Node.js was updated to v20.19.0 in version 1.100.0
  • chore: bump electron@34.5.1 microsoft/vscode#246817
• Stackblitz Codeflow was updated to Node.js v20.19.x on April 10, 2025
  • Support later versions of Node (or make version configurable) stackblitz/webcontainer-core#560 (comment)
• VS Code has supported ESM extensions since version 1.100.0
  • ESM for extensions microsoft/vscode#245214
• Stylelint has supported ESM plugins since version 16.0.0
  • Add support for ESM plugins stylelint/stylelint#7339
• ESLint supports ESM plugins with flat config
• TypeScript Language Service Plugin has no plans to support ESM.
  • TypeScript plugins do not support ESM-only packages microsoft/TypeScript#62326
• @vscode/test-cli supports ESM Extensions. However, due to a VS Code bug, import 'vscode' in test files causes a deadlock.
  • Support for ESM extensions microsoft/vscode-test-cli#77 (comment)

Based on the above, the following changes can be implemented.

• core, codegen, stylelint-plugin, and eslint-plugin can be migrated to ESM
• ts-plugin can migrate modules other than the entry point to ESM
• vscode can migrate to ESM, but workarounds to avoid deadlocks must be implemented in test files.
  • Using require(esm) breaks the mechanism for intercepting the vscode module microsoft/vscode#285297 (comment)

[changeset-bot]

🦋 Changeset detected

Latest commit: 4723762

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 6 packages

Name	Type
@css-modules-kit/ts-plugin	Minor
@css-modules-kit/stylelint-plugin	Minor
@css-modules-kit/eslint-plugin	Minor
@css-modules-kit/codegen	Minor
css-modules-kit-vscode	Minor
@css-modules-kit/core	Minor

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