fix(cli): move api-block assertions into a real .ts file

skipLibCheck exempts .d.ts contents from being checked, so assertions
written inside wrnexus.generated.d.ts were never evaluated by tsc.
Emit them into wrnexus.generated.api-checks.ts instead, referencing
the WRNexusGenerated namespace's helper types (which stay in the
.d.ts). Track the new generated file in check:generated-types.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

examples/basic-app/app/types/wrnexus.generated.api-checks.ts

@@ -0,0 +1,7 @@
+// AUTO-GENERATED by `wrnexus generate types` - do not edit.
+//
+// Type-only assertions for sectioned `api` blocks. Kept as a real .ts file (not
+// wrnexus.generated.d.ts) because `skipLibCheck` exempts .d.ts contents from being
+// checked; this file is compiled and checked normally by the project's own tsc.
+
+export {};

examples/basic-app/app/types/wrnexus.generated.d.ts

@@ -57,4 +57,8 @@ declare namespace WRNexusGenerated {
     "welcome-email": QueuePayload<(typeof import("../queues/welcome-email.ts"))["default"]>;
   }
   type ApplicationConfig = (typeof import("../../wrnexus.config.ts"))["default"];
+  type AssertAssignable<Actual, Expected> = [Actual] extends [Expected] ? true : false;
+  type __wrn_expect_true<T extends true> = T;
+  type ApiInput<P extends ApiRoute, M> = ApiContracts[P][M]["input"];
+  type ApiOutput<P extends ApiRoute, M> = ApiContracts[P][M]["output"];
 }