NSwag for WASM+Identity

We scrapped Swashbuckle, but NSwag looks good as a replacement ...

```xml
<PackageReference Include="NSwag.AspNetCore" Version="14.0.2" />
```

```csharp
builder.Services.AddOpenApiDocument();
```

In the Dev environment ...

```csharp
app.UseOpenApi();
app.UseSwaggerUi();
```