Mob Health Scaling

Mobs gain extra health based on the Area Difficulty. There are four primary scaling modes:

1. ADD: Adds a flat amount of health based on difficulty (e.g., +20 HP regardless of base health).
2. MULTI: Multiplies the mob's base health by a factor derived from difficulty.
3. MULTI_HALF: Multiplies health, but the multiplier is reduced for mobs that already have high base health (default mode).
4. MULTI_QUARTER: A more conservative version of MULTI_HALF for minimal scaling on bosses.