Generates bUnit component tests for Blazor components (.razor): renders the page, fills and submits its forms, asserts the rendered markup and the validation and error messages the use case states, and replaces the handlers and services it injects with test doubles, one test per scenario and business rule tagged with [UseCase]. Use when the user asks to "write bUnit tests", "test a Blazor component", "test the Razor page of UC-001", "create UI tests for Blazor", or mentions bUnit or xUnit rendering tests. Backend tests are /dotnet-test, browser tests /playwright-test.