US 02.03.01

As a player, I want to be able to browse QR codes that other players have scanned.

Acceptance criteria

There is a global database that contains the hash of all scanned QR codes and:
- The number (N) of players who scanned it
- The score (score) of that hash
- other shared data relating to that QR code
When a player adds a QR code, the associated hash N value is incremented by 1 (or created if it doesn't already exist)
When a player removes a QR code, the associated hash N value is decremented by 1
If the N value of any hash in the global database equals 0, then that hash is removed from the database.
Users can view a list representation of this global database to browse all scanned QR codes