The Obama administration is leading a global effort to deploy “shadow” Internet and mobile phone systems that dissidents can use to undermine repressive governments that seek to silence them by censoring or shutting down telecommunications networks. The effort includes secretive projects to create independent cellphone networks inside foreign countries, as well as one operation out of a spy novel in a fifth-floor shop on L Street in Washington, where a group of young entrepreneurs who look as if they could be in a garage band are fitting deceptively innocent-looking hardware into a prototype “Internet in a suitcase.”