delay gold reward from beasts until level up

[loothero]

To add more unknown information to the game and add additional excitement to the level up experience, we could utilize the level seed to determine how much gold was earned from each beast.

To support this, we would add a defeated_beasts counter on the adventurer struct which records the number of beasts defeated during the level. At the end of the level, we would then generate a random amount of goal for each defeated beast.

We could greatly enhance this feature and the player experience of leveling up by adding a "Level Complete" interface at the end of each level. This would replace our current interface of "Generating verifiable randomness for level X" with a more exciting ux focused on a recap of the level, highlighting each of the beasts defeated and once VRF comes in, showing the gold bonus gained from each defeated beast.