Types are incompatible with NodeNext tsconfig

Describe the bug

The exported types don't use extensions, so they're faux esm and fail to import in modern moduleResolution settings.

Reproduction

https://arethetypeswrong.github.io/?p=wxt%400.20 (this is probably more minimal than my actual project)

Steps to reproduce

Given tsconfig.json of a wxt starter, add:

{
  "compilerOptions": {
    "module": "nodenext",
    "moduleResolution": "nodenext", 
  }
}

tsc should complain that Module '"wxt"' has no exported member ...

System Info

n/a

Used Package Manager

pnpm

Validations

• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

Start with the minimal reproduction at the linked arethetypeswrong.dev report and the wxt starter's tsconfig.json, then run tsc with module and moduleResolution set to nodenext. Trace how the package's exported types are generated and verify that the reported wxt exports resolve without TypeScript errors under NodeNext.