.NET test authoring

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Apply test-authoring.

• Place a test at the narrowest layer that proves the behavior.
• Batch native or external selection where the project requires it.
• Isolate process and filesystem state.
• Assert a serialized contract. Do not assert a private implementation detail.
• Keep a helper typed and reusable only when it removes repeated setup without hiding an expectation.
• Keep portable library tests separate from rendered application tests.
• Batch compatible native targets in one selection pass so one shared build validates that source set.

Consumer wrapper owns: solution layout, test frameworks, native dependencies, and coverage policy.