Fixes #194. Some tests fail due to different cultures.

[BDisp]

Fixes #194

[chatgpt-codex-connector]

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[tig]

Concern: Process-global state mutation in parallel tests

CultureInfo.DefaultThreadCurrentCulture is process-wide. Setting it in each test class constructor races with parallel tests in the same assembly"

Suggested fix: Replace all three constructors with a single <InvariantGlobalization>true</InvariantGlobalization> in the integration test .csproj:

<PropertyGroup>
  <InvariantGlobalization>true</InvariantGlobalization>
</PropertyGroup>

This:

• Applies invariant culture at the runtime level (no race)
• Eliminates per-class boilerplate
• Automatically covers new test classes
• Doesn't mutate shared state from test code

If invariant globalization is too broad (e.g., some tests intentionally verify locale behavior), an alternative is a shared xUnit IAssemblyFixture that sets culture once at assembly startup.