Replaces the prior dotnet-aspnetcore skills (dotnet-webapi, minimal-api-file-upload, configuring-opentelemetry-dotnet, convert-blazor-server-to-webapp) with a focused REST API skill set.
Adds two skills with Vally evals over a shared e-commerce store fixture (1:1, 1:M, M:N relationships):
- author-minimal-api-endpoints: typed Results<...>/TypedResults, correct status codes (201+Location, 204, 404, 400), input validation via ProblemDetails.
- structure-api-business-logic: thin endpoints over a service layer that returns a hand-rolled Result<T> with a semantic ErrorType; endpoint translates it to HTTP; service takes DTOs/commands with manual mapping and never returns ASP.NET result types.
Both validated baseline-vs-skilled over 3 runs (endpoints 3.17->4.92/5, structure 2.56->5.00/5; no regressions).
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>