After much tiral and error, I've found this command seems to do mostly what I want. The output is a new HTML file which references a script called 'all-classes.js' which contains all my JS code in one file.

sencha compile -classpath=app.js,app,sdk/src page -in=src.html -out=build.html
However, when I load the new build.html, I get a error in the JS console.

Uncaught Error: [Ext.createByAlias] Cannot create an instance of unrecognized alias: widget.form
I've looked through the all-classes file and the Ext.form.Panel is definitely present in the file (with the alias 'widget.form') so I'm now lost. What can I do next? Any help resolving this is appreciated.