fix(eval): load ESM import edges asynchronously (#385)

* fix(eval): load external import edges asynchronously

When a broker-fallback barrel is linked in a vm.SourceTextModule, synchronously requiring an ESM child can trigger Node's status-0 assertion. Pass the resolution kind into the external loader and use import() for import and dynamic-import edges, while preserving require for JSON and native assets. Add a dual-package barrel regression fixture that fails with the original Unexpected module status 0 error.

Co-authored-by: Codex <noreply@openai.com>

* test(cli): remove obsolete require fallback assertion

The evaluator now loads import edges with import(), so this CLI integration test should assert successful extraction rather than the old fallback diagnostic.

Co-authored-by: Codex <noreply@openai.com>

* Keep eval.require meaningful and CJS exports intact when loading externals async

Switching `import`-edge externals to import() is needed — the require() that
trips "Unexpected module status 0" also poisons the entry for any later
import(), so it cannot be retried — but doing it unconditionally routed every
CommonJS dependency around eval.require and around require()'s runtime export
enumeration. Reuse the require-policy check on the new path and read
module.exports back out of the CJS cache so dynamically assigned exports stay
importable, which also lets the CLI keep asserting the require-fallback
diagnostic.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* fix(eval): preserve builtin import handling

Keep Node builtin imports on the runner's existing require path so eval.require does not classify them as runtime fallback dependencies. Add a regression covering a custom-resolved node:path import with eval.require='error'.

Co-authored-by: Codex <noreply@openai.com>

* fix(eval): resolve bare external imports from importer

---------

Co-authored-by: Codex <noreply@openai.com>
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Anton Evzhakov <anton@evz.name>