Analytics backend

<img width="1787" height="1100" alt="Image" src="https://github.com/user-attachments/assets/e75034ba-6459-4801-b533-04764924f930" />

To support this, we'll probably need to add a bunch of new functionality to the CloudFlare worker.

Add some `/metrics` endpoints that return:
* top games all time
* ...other metrics 