C# Blazor tutorial/tooling requires user pick ".sln" and not ".slnx"

### URL

https://dotnet.microsoft.com/en-us/learn/aspnet/blazor-tutorial/intro

### Operating system

macos

### More information about your system

* macOS 26.0.1 (25A362)
* Mac M1
* VS Code 1.105.1
* C# dev kit 1.70.3

### Description

Following the tutorial, the project generation step asks the user to pick .sln or .slnx format. I originally picked .slnx and this resulted in the Solution Explorer not appearing. I also don't think the Run and Debug properly provided the option to run, but I don't really remember. I restarted the tutorial and picked .sln instead.

### dotnet --info

.NET SDK:
Version: 9.0.306
Commit: cc9947ca66
Workload version: 9.0.300-manifests.87361a52
MSBuild version: 17.14.28+09c1be848

Runtime Environment:
OS Name: Mac OS X
OS Version: 26.0
OS Platform: Darwin
RID: osx-arm64
Base Path: /usr/local/share/dotnet/sdk/9.0.306/

.NET workloads installed:
There are no installed workloads to display.
Configured to use loose manifests when installing new manifests.

Host:
Version: 9.0.10
Architecture: arm64
Commit: e1f19886fe

.NET SDKs installed:
9.0.306 [/usr/local/share/dotnet/sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 9.0.10 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 9.0.10 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

Other architectures found:
None

Environment variables:
Not set

global.json file:
Not found

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