This looks solid! In an effort to fortify your motivation and help you foster an indie-dev mindset, I will check back on this from time to time. I am excited to see what you come up with; this design document excites the idle-gamer inside. I, too, started my indie dev journey creating an idle game. Each time I feel ready to move on to the next thing, I dive deeper into a system I've already made and find more to learn. I digress, stay committed!
I would wish you luck, but you don't need it :)