Pin multi-outcome command responses against Arc for .NET

[woksin]

Arc for TypeScript 0.39.0 pins how commands with several possible outcomes behave on the wire against Arc for .NET, and lets the proxy generator accept outcome alternatives that share one client type. npm publication remains disabled.

Added

• Paired conformance checks against Arc for .NET 22.23.0 for commands whose handlers return OneOf/Result alternatives: a DTO or primitive answers 200 with it as response, a validation branch answers 400, a denial 403, a tuple's validation result replaces its response, and no discriminator is added to the wire. An arbitrary Result error DTO in .NET is an ordinary 200 response; in TypeScript, return it with response(...) to get the same result, or use rejected(...)/denied(...) for failures. The suite now runs 279 checks.

Changed

• The proxy generator analyzes every execution path of a command's return type, including Outcome helpers, promises, aliases and nested tuples, and accepts alternatives that resolve to the same client type. Literal unions such as boolean, enums and 'a' | 'b', with or without null/undefined, keep their full type, distinct concepts fall back to their shared primitive, and arrays that mix Chronicle event types are omitted from the client response as before.
• Alternatives that need different client types, including two structurally identical but distinct DTO classes, now fail generation with guidance to return one response DTO with a status field. Arc for .NET's generator picks one of them instead, which the client can't decode reliably.
• Generated metadata for queries returning boolean, enums or literal unions now names the element type, so OpenAPI describes their data.
• The command outcomes guide describes how to model several business outcomes.

Refs #90