Yes, there is already code to list all the files in a directory, that's what local saves do. To use local saves, put your saves in Saves/, then ctrl+click the save browser button and it will open the local save browser instead.
stamps are just a legacy thing, local saves are better and can actually have names :). The "Rescan Stamps" button will also do what you want though.
It has to be exactly 10 characters long (a timestamp). That's why you should use local saves, stamps can't be named.
Edit: naming it Hello_____.stm might work ... but weird. I know local saves aren't good for bombs but maybe eventually it will be rewritten to all be one thing.