Resolves [Code Scanning Alert
180](https://github.com/twentyhq/twenty/security/code-scanning/180).
- Normalize unexpected GraphQL errors in convertExceptionToGraphql to a
generic "Internal Server Error" instead of exposing exception.name
directly to clients.
- Only attach stack and response (original error message) in
development, so production responses don’t leak internal class names,
implementation details, or stack traces, while observability is
preserved via `ExceptionHandlerService`/Sentry.
- Keep behavior consistent with `convertHttpExceptionToGraphql`, which
also only exposes detailed response and stack information when `NODE_ENV
=== DEVELOPMENT`.
