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>