I'm attempting to write a Thunderbird add-on using the MailExtension API. I've created a folder with a manifest.json and background.js, and I've got the Hello World example code entered into the files. I'm trying to install that Hello World example code into Thunderbird as an add-on, but I can't find any documentation that explains how to do that. The Mozilla documentation for the Hello World example project suggests downloading all 3.5 GB of the full Thunderbird source code, and building a whole new thunderbird binary with the changes built in. Obviously that's insane, and I can't imagine it's the proper procedure for building a simple add-on comprised of less than 15 lines of code. How would I go about adding a simple custom-made add-on into the standard, already-installed version of thunderbird that's currently running on my system? Thanks in advance!