1.31.4

(fix): Fix sub-package ErrorCodes maps being empty when errors are declared in a different namespace than the endpoints that reference them. The generator now groups errors by the service namespace that uses them (via endpoint error references) instead of by where they are declared. This ensures that sub-packages like audio/ correctly get populated ErrorCodes with typed errors (e.g. BadRequestError, UnauthorizedError) instead of an empty map that would cause API errors to be returned as generic *core.APIError.