agent skills and aspire CLI support for nested repo structure

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Is your feature request related to a problem? Please describe the problem.

I'm trying to use the agent skills and `aspire` ClI (aspire new / aspire init) to scaffold a C# AppHost.

I'd like to achieve the following repo structure.

```
/ (repo root)
/SolutionName.slnx
/aspire.config.json
/nuget.config
/Directory.Build.props
/Directory.Packages.props
/src
/src/SolutionName.AppHost/
/src/SolutionName.ServiceDefaults/
/src/SolutionName.Backend.Tests/
/tests/SolutionName.Backend.Tests/
/tools/SolutionName.DbMigration/
/docs/
```
etc.

I created an empty repo repo and added an empty solution, the `nuget.config` and the `Directory.*.props` files to it like so:
```
/SolutionName.slnx
/nuget.config
/Directory.Build.props
/Directory.Packages.props
```

It is possible to use `dotnet new` with a specific output folder. However, the agent skills and `aspire new` and `aspire init` do not seem to along nicely - when specifying an output folder they do not use the existing solution and they drop all their files in the specified output folder rather than integrating with the existing files.

### Describe the solution you'd like

- `aspire init` and `aspire new` recognize existing solution and configuration files
- skills like `aspire-init` and `aspireify` support this structure

### Additional context

Please note that this is a common structure; the Aspire repo itself follows this structure: