[dev #2] Random Reward

Implemented Stage Clear Rewards

Bosses have unique rewards, which are drawn first.
If the player does not win the draw for the unique reward, a secondary draw is performed for rarity levels 01–05, based on draw rates set individually for each boss.

Displaying 3D model chests and 2D model chests on the result screen, as well as storing them in the player’s inventory,
was challenging to implement in Game Creator 2.
It might have been easier to handle with coding directly.

That said, I now have a deeper understanding of how to use GC2 and Inventory 2 than before.