fix(js): use the stealth transport for ES modules

[xrip]

Summary

• load ES modules through the page stealth client when stealth mode is enabled
• preserve the existing non-stealth loader path
• keep module fetching aligned with the page transport and profile

Source fork commit: fa23762.

Validation

• the Rust change was reviewed against the existing module loader paths
• the local release check reached the V8 build but exceeded the tool window without a compiler error; CI should provide the full build result.