Plugin install fails: dotnet-aspnet not found in marketplace

Question

## Description

Running the following command fails with "Plugin not found in any marketplace":

```
/plugin install dotnet-aspnet@dotnet-agent-skills --force
```

## Error

```
Plugin "dotnet-aspnet" not found in any marketplace
```

## Expected Behavior

The `dotnet-aspnet` plugin from the `dotnet-agent-skills` source should be discoverable and installable.

## Environment

- Platform: Windows 11
- Claude Code version: (latest)