Take Aspire 13.5.0, hold xunit.v3 at 3.x, move dotnet test to MTP mode

[KaliCZ]

Replaces #22, which can't go green as-is.

Why #22 fails

The build actually succeeds — it's dotnet test that fails:

Microsoft.Testing.Platform.MSBuild.targets(320,5): error : Testing with VSTest target is
no longer supported by Microsoft.Testing.Platform on .NET 10 SDK and later.

Two separate problems hide behind that, and only one of them is fixable today.

xunit.v3 4.0.0 is not adoptable — held

FsCheck.Xunit.v3 3.3.4 (the newest release, Jul 2026) is built against
xunit.v3.extensibility.core 3.0.1. xunit.v3 4.0.0 changed the signature of
TestIntrospectionHelper.GetTestCaseDetails, so with 4.0.0 in place every
[Property] test dies during discovery:

Xunit.MicrosoftTestingPlatform.XunitException: Exception during discovery:
System.MissingMethodException: Method not found: '...TestIntrospectionHelper.GetTestCaseDetails(...)'
   at FsCheck.Xunit.PropertyDiscoverer...Discover(...)

8 of 13 unit tests fail. It's a runtime binding break, so there's nothing to fix on
our side — it needs a FsCheck release built against xunit.v3 4.x. Added a dependabot
ignore for the major, same shape as the existing typescript hold.

The MTP migration isn't blocked — done

xunit.v3 4.x pulls Microsoft.Testing.Platform 2.x, which removed the VSTest bridge on
the .NET 10 SDK. That's the error above, and it's independent of the FsCheck problem,
so it's migrated now rather than left to rediscover later:

• global.json gains test.runner: Microsoft.Testing.Platform — the replacement opt-in
• TestingPlatformDotnetTestSupport dropped from both test projects; it's obsolete under MTP mode

This works with xunit.v3 3.2.2 today and means the only thing standing between us and
xunit.v3 4.x is FsCheck.

Aspire 13.5.0 — taken

Builds clean, 0 warnings (and TreatWarningsAsErrors is on, so no obsolete-API
warnings either). None of the 13.5 breaking changes touch the AppHost.

Verification

dotnet build ProductReviews.slnx --no-restore -c Release → 0 warnings, 0 errors.
dotnet test --no-build -c Release → 43/43 passing, both projects, integration tests
against real Postgres via Testcontainers. Bare dotnet test still discovers the
.slnx in MTP mode, so no CI or docs command changes.

🤖 Generated with Claude Code