Improve the UI

[rbanks54]

Make the UI more dashboard-y so we can show how different read models and domain services can be fronted by an API gateway, and how a single page can be rendered using data from different contexts.

[rbanks54]

For reference this means I want to do something like the following:

• [ ] throw out the current UI
• [ ] replace with a SPA app that has dashboard type panels on it, with multiple parts (using React, maybe?)
• [ ] have an admin panel for adding new products.
• [ ] have a cashier panel where new orders can be added, and payment made.
• [ ] have a barista queue panel, showing what orders need to be prepared, and a button to mark an order as prepped.
• [ ] allow cashiers to complete an order when payment is made and the order has been prepared by the barista
• [ ] refresh the UI when relevant events occur