feat: add health-potion functionality

feat: add health-potion functionality

Once the user has health potions, they are displayed on the Inventory
page. In order to do that we had to split up inventory + profile. We
also introduced the new "Modal" system which utilizes the default
`<dialog>` HTML element to display more information about an item.

It also introduces the ability to filter equipment in shops based on
whatever it actually sells. The idea is that you can switch to a tab
that matches what you're trying to buy.