This problem has been solved. Solution in Post #6.
In short, my application works great with Ext.Loader enabled but not built. However, after disabling Ext.Loader and building my application, it continues to try and load every file that has already been defined in single file that SenchaCmd compiled. It tries to load all of the files with an incorrect path and thus fails.
How can I stop my built, single js file from using Ext.Loader to load all of my classes? All of the classes are already defined in the single js file, but Loader doesn't seem to either notice or care that literally the entire application has already been loaded.
Here's what's happening in Firebug (this is a snippet... it goes on for much longer):
I don't know why it's using NS as the path, as that should have translated to "app".
Error: [Ext.Loader] Failed loading 'NS/controller/Authentication.js', please verify that the file existsError: [Ext.Loader] Failed loading 'NS/controller/User.js', please verify that the file exists
Error: [Ext.Loader] Failed loading 'NS/store/Users.js', please verify that the file exists
Error: [Ext.Loader] Failed loading 'NS/view/UserEditor.js', please verify that the file exists
I have been working on this for days and any help would be appreciated. Thanks!