HOWEVER STERN THE WATCHDOGS at the INS get, they can't stop the flood of new world-music CDs. (Only you at home downloading with your computer can do that.) Boston's own Leah Callahan, formerly of Turkish Delight and Betwixt, makes her solo-artist recording debut with the release of Even Sleepers (Baraca Records) on October 7. Callahan's new work is inspired by, among other things, vocal music from Egypt, Portugal, and the Balkans. She'll be playing at Jacque's (617-426-8902) in Bay Village every second Friday this fall, starting this Friday, September 12.