I'm also working on implementing jqGrid in Zend Framework. I see your definition of the jqGrid in your .js file, but I don't see where you actually send the data to the grid. Your $result table needs to be converted to json for your grid to work.
I'm also in the process of getting the json type grid to work, having successfully created a grid using a locally defined array in my javascript. Once I figure that out I will be happy to share what I discover.