Test providers SPI

Providers are responsible for turning rules (and other logic) into generated TestCase objects.

TestCaseProvider

Providers implement TestCaseProvider<T> and return Outcome<List<TestCase>>.

Guidelines:

• Do not mutate inputs (valid case, context, OpenAPI models).
• Preserve deterministic ordering.
• Prefer composition of smaller providers per concern.
• Use provider boundary helpers (runProviderSafely) so exceptions become structured failures.