[Bug]: `build` and `setuptools` being missing produces odd errors

### What happened?

In order for us to do sdist builds for users, we need `build` at a minimum and often `wheel` and `setuptools` too. The UV extension produces the very much not obvious error

```
Error in fail: Unable to resolve a default version for requirement "build" in @@//cases/uv-default-version-xxx:uv.lock
```

if the user hasn't provided these dependencies. We should try to provide a more specific warning if we can.

### Version

Development (host) and target OS/architectures:

Output of `bazel --version`:

Version of the Aspect rules, or other relevant rules from your
`WORKSPACE` or `MODULE.bazel` file:

Language(s) and/or frameworks involved:

### How to reproduce

```shell

```

### Any other information?

_No response_

Start by tracing the UV extension's handling of sdist builds and missing build, wheel, or setuptools dependencies. Reproduce the shown resolution error with a project that omits these dependencies, then identify the existing warning or error path. Done means users receive a more specific warning instead of the default-version resolution error.

Written by the indexing model from the issue text.