Generator: duplicate class names across packages cause TS barrel export collision

[jsenko]

The GenerateCoreTs barrel file generator creates export * from "..." for every .ts file. When two modules in different packages export the same simple name (e.g., Schema trait in models/ and Schema union in models/jsonschema/), the TS compiler rejects the duplicate export.

Current workaround: rename the type alias to avoid collision.

Long-term fix options:

1. GenerateCoreTs could detect duplicate names and use named re-exports
2. The generator could ensure unique simple names across all packages
3. Future: OpenAPI/AsyncAPI should use JSON Schema models directly instead of duplicating schema entities, eliminating the shared Schema trait