fix: preserve original extension when extension redirection is disabled

[Timeless0911]

Summary

when redirect.js.extension set to false

source

export * from './bar.node';
export * from './bar.node.js';
export * from './bar.node.ts';
export * from './bar';
export * from './baz-folder';
export * from './foo.js';
export * from './foo.ts';

before

export * from "./bar.node.ts";
export * from "./bar.node.ts";
export * from "./bar.node.ts";
export * from "./baz.ts";
export * from "./baz-folder/index.ts";
export * from "./foo.ts";
export * from "./foo.ts";

now

export * from "./bar.node";
export * from "./bar.node.js";
export * from "./bar.node.ts";
export * from "./baz";
export * from "./baz-folder/index";
export * from "./foo.js";
export * from "./foo.ts";

Related Links

close: #1368

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

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[Copilot]

Pull request overview

This PR fixes the handling of import path extensions when extension redirection is disabled in bundleless mode. The fix ensures that when redirect.js.extension is set to false, the original file extensions in import statements are preserved rather than being forcibly replaced or removed.

Key Changes

• Modified extension redirection logic to preserve original JS extensions when redirection is disabled
• Fixed handling of unresolved modules to prevent incorrect extension manipulation
• Added comprehensive test coverage for various edge cases including .node, .node.js, .node.ts extensions

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/core/src/config.ts	Implements the core fix: preserves original extensions when jsRedirectExtension is false by checking if the original extension matches JS_EXTENSIONS_PATTERN; also fixes handling of unresolved modules to prevent processing
tests/integration/redirect/js/src/index.ts	Adds test cases for various extension scenarios including .node, .node.js, .node.ts, .js, and .ts extensions
tests/integration/redirect/js/src/not-resolved.ts	New test file with unresolved imports to verify they remain unchanged
tests/integration/redirect/js/src/bar.node.ts	New test file to support .node extension test cases
tests/integration/redirect/js/tsconfig.json	Adds noEmit and allowImportingTsExtensions to support importing files with .ts extensions in tests
tests/integration/redirect/js.test.ts	Adds test expectations verifying that original extensions are preserved when redirection is disabled
website/docs/en/config/lib/redirect.mdx	Updates English documentation to clarify extension redirection behavior
website/docs/zh/config/lib/redirect.mdx	Updates Chinese documentation to clarify extension redirection behavior
packages/plugin-dts/README.md	Updates plugin documentation for consistency with the improved behavior

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