Maintainability roadmap

[peppidesu]

The source code is in very poor condition at the moment:

• No tests whatsoever
• Messy CSS with lots of duplication
• Game logic in root of application

And so on.

These need to be addressed before moving on with feature additions, so that technical debt stays manageable and game-breaking bugs are caught before production.

[peppidesu]

refactor merged into main, should fix a lot of these issues