migrate-mstest-v1v2-to-v3

# MSTest v1/v2 -> v3 Migration Migrate a test project from MSTest v1 (assembly references) or MSTest v2 (NuGet 1.x-2.x) to MSTest v3. MSTest v3 is **not binary compatible** with v1/v2 -- libraries compiled against v1/v2 must be recompiled. ## When to Use - Project references `Microsoft.VisualStudio.QualityTools.UnitTestFramework.dll` (MSTest v1) - Project uses `MSTest.TestFramework` / `MSTest.TestAdapter` NuGet 1.x or 2.x - Resolving build errors after updating MSTest packages from v1/v2 to v3 - Replacing `.testsettings` with `.runsettings` - Adopting MSTest.Sdk or in-assembly parallel execution ## When Not to Use - Project already uses MSTest v3 (3.x packages) - Upgrading v3 to v4 -- use `migrate-mstest-v3-to-v4` - Migrating between frameworks (MSTest to xUnit/NUnit) ## Inputs | Input | Required | Description | |-------|----------|-------------| | Project or solution path | Yes | The `.csproj`, `.sln`, or `.slnx` entry point containing MSTest test projects | | Build command | No | How to build (e.g., `dotnet build`, a repo build script). Auto-detect if not provided | | Test command | No | How to run tests (e.g., `dotnet test`). Auto-detect if not provided | ## Breaking Changes Summary MSTest v3 introduces these breaking changes from v1/v2. Address only the ones relevant to the project: | Breaking Change | Impact | Fix | |---|---|---| | `Assert.AreEqual(object, object)` overload removed | Compile error on untyped assertions | Add generic type: `Assert.AreEqual<T>(ex...