feat: add the rating page, that will display the previous 7 days ratings

[yurijmikhalevich]

1. Add api/rating.get.ts (check out api/state.get.ts for reference), that will

• fetch game stats from the database
• compute ratings
• return it to the client

2. Add pages/rating.vue that will

• fetch the rating data
• display it
  It is better to build the actual rating table in a separate component, for example, components/Rating.vue, so that it's easy for us to use it in other places.

Feel free to create multiple PRs for this Issue if you want 😄