New command group for OpenAPI spec generation and SDK codegen:
- `core api spec` generates OpenAPI 3.1 spec (JSON/YAML) from route groups
- `core api sdk` generates client SDKs via openapi-generator-cli
- Adds go-api dependency for SpecBuilder, ExportSpec, SDKGenerator
Co-Authored-By: Virgil <virgil@lethean.io>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>