Restore C# emitter schema spread

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: ArcturusZhang

packages/http-client-csharp/emitter/src/options.ts

@@ -46,7 +46,7 @@ export const CSharpEmitterOptionsSchema: JSONSchemaType<CSharpEmitterOptions> =
   type: "object",
   additionalProperties: false,
   properties: {
-    "api-version": UnbrandedSdkEmitterOptions["api-version"]["api-version"],
+    ...UnbrandedSdkEmitterOptions["api-version"],
     "generate-protocol-methods": {
       type: "boolean",
       nullable: true,