Failed to create snack: Missing required file: App.js

### Summary

I setup my project using `create-expo-app@latest`, which comes with the expo-router boilerplate. Then, I moved everything code related into the `/src` folder.

I uploaded the project to this GitHub repo: [onyedikachi23/nerdytok](https://github.com/onyedikachi23/nerdytok).

However, visiting [snack.expo.dev](https://snack.expo.dev/) and trying to import the repo gives the error:

```

An error occurred during import.
This could be because the data provided was invalid,
or because the repository referenced is not a properly
formatted Expo project.

Failed to create snack: Missing required file: App.js.

```

### What platform(s) does this occur on?

Android, iOS, Web

### SDK Version

51

### Reproducible demo or steps to reproduce from a blank project

Visit [snack.expo.dev](https://snack.expo.dev/) and try to import the GitHub repo: [onyedikachi23/nerdytok](https://github.com/onyedikachi23/nerdytok).

Reproduce the import of onyedikachi23/nerdytok in Snack and start from the missing App.js validation reported in the error. Trace how Snack handles an Expo Router project with code under /src; done means the reported repository imports successfully without the missing-file error.

Written by the indexing model from the issue text.