Replace the local navigation extension with centralized helpers from krow_core: add krow_core dependency and imports, remove src/presentation/navigation/client_auth_navigator.dart and its export, and update Module routes to use ClientPaths constants. Update page callbacks to use Modular.to.toClientSignIn/toClientSignUp/toClientHome instead of the old push/navigate extension and replace hard-coded route strings with ClientPaths. This centralizes route definitions and removes duplicated navigation logic.