Alright, I've had a peek in the database file last night. Here's my two cents.
The password salt is stored in the database, which is great. But we don't know what sort of encryption is used, or what the algorithm is. (E.g. hash($password + $salt) or hash(hash($password) + $salt), etc.) If we have the algorithm and the encryption type, we can let players login with their account on a website.
As far as I know, SQLite is pretty similar to MYSQL. It lacks a few advanced features like RIGHT JOIN, Foreign Key constraints and some permissions stuff, though as long as you stick to basic queries you should be fine. Personally though, writing SQL in a web app is old hat. I would use a framework with a working ORM instead and let that take care of your database functions. I use Laravel myself, though I've heard good things about Medoo, which is a far smaller app. I'll mess around with this more over the weekend.