fix: the require() ESM problem when node < 20.19

[yifancong]

Summary

• Fix the require() ESM problem when node < 20.19
• The @rsbuild/plugin-check-syntax prebundle has error, so move to dependencies.
• When in cjs artifacts,need to use the proxy.cjs, and use proxy-esm.js in esm artifact.
• Optimize the e2e tests little problems

Related Links

#1339

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[Copilot]

Pull Request Overview

This PR fixes ESM compatibility issues for Node.js versions below 18.19 by updating import statements and resolving loader paths more robustly.

• Replaced fs-extra/esm imports with standard fs-extra imports
• Updated file operations to use Node.js built-in fs methods instead of fs-extra in some cases
• Added fallback logic for loader path resolution to handle both ESM and CJS environments
• Moved @rsbuild/plugin-check-syntax from devDependencies to dependencies to avoid prebundling issues

Reviewed Changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
packages/utils/src/build/file/index.ts	Changed fs-extra import from ESM-specific to standard import
packages/sdk/src/sdk/sdk/index.ts	Replaced fs-extra method with Node.js built-in fs methods
packages/sdk/src/sdk/sdk/core.ts	Changed from sync to async fs-extra method
packages/core/src/inner-plugins/plugins/loader.ts	Added fallback logic to resolve proxy loader paths
packages/core/src/build-utils/build/utils/loader.ts	Updated fs-extra import from ESM-specific to standard
packages/core/rslib.config.ts	Added comment about ESM file handling
packages/core/prebundle.config.mjs	Removed @rsbuild/plugin-check-syntax from prebundle dependencies
packages/core/package.json	Moved @rsbuild/plugin-check-syntax to production dependencies

Files not reviewed (1)

• pnpm-lock.yaml: Language not supported

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