You're saying you're not using EJB, but the code looks like a real stateless session bean to me!
To be able to find this bean, Seam needs some additional help. I assume that you have packed this bean in a Jar for deployment and if so, it should contain a - empty - seam.properties file. Furthermore you need additional configurations in components.xml
There is really no need to use jdbc code, because the Entitymanager gets directly injected, assuming that there is a persistency context avalable.