fix: cjs import.meta.url shims in async chunks

[Timeless0911]

Summary

import.meta.url shims should work correctly in async chunks since chunk.name may be undefined if no magic comments set.

Related Links

close: #1277

Checklist

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

[Copilot]

Pull Request Overview

This PR fixes the generation of import.meta.url shims in CommonJS async chunks by ensuring the shim injection tracking occurs before checking if the chunk name is defined, preventing async chunks without magic comments from being skipped.

• Moved shimsInjectedAssets.add(filename) before the early return when chunk.name is undefined
• Added test coverage for import.meta.url usage in dynamically imported modules
• Verified that the shim is correctly generated in async chunks

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
packages/core/src/plugins/EntryChunkPlugin.ts	Moved shim tracking before name check to handle async chunks
tests/integration/shims/cjs/src/index.ts	Added dynamic import test case
tests/integration/shims/cjs/src/dynamic.ts	New file testing import.meta.url in async chunk
tests/integration/shims/index.test.ts	Added test assertions for async chunk shim generation
tests/integration/shims/cjs/rslib.config.ts	Formatting changes only

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