test(generate): add sdk drift guardrails

[kitlangton]

Summary

• add a focused OpenAPI regression test to keep the public question.reply request body inline
• add bun run generate:check to regenerate the SDK/OpenAPI and fail on drift
• keep the current route implementation unchanged while adding guardrails around the contract

Testing

• bun run test test/util/effect-zod.test.ts test/server/question-openapi.test.ts
• bun run typecheck
• bun run generate:check