Core/Stats: Base stats accumulate on level-up after #31936 #32042

Description

Description

After #31936 / commit e45b30bc681f, player base stats stack on every level-up until relog.

The regression appears to come from the new Unit::SetCreateStat implementation:

void Unit::SetCreateStat(Stats stat, float val) { UnitMods const unitMod = static_cast<UnitMods>(UNIT_MOD_STAT_START + AsUnderlyingType(stat)); HandleStatFlatModifier(unitMod, BASE_VALUE, val, true); }

must be void Unit::SetCreateStat(Stats stat, float val) { UnitMods const unitMod = static_cast<UnitMods>(UNIT_MOD_STAT_START + AsUnderlyingType(stat)); SetStatFlatModifier(unitMod, BASE_VALUE, val); }

Expected behaviour

SetCreateStat should replace the fixed create stat for the current level, not accumulate it across levels.

Steps to reproduce the problem

1. Log in on a low-level character.
2. Note the current level and max HP.
3. Gain exactly one level using normal XP or .levelup 1.
4. Note max HP immediately after the level-up.
5. Relog.
6. Compare max HP before and after relog.

Observed:

Level 2 after relog: 321 HP
Level 3 immediately after level-up: 672 HP
Level 3 after relog: 351 HP

### Branch

master

### TC rev. hash/commit

-

### Operating system

Windows 11 x64

### Custom changes

no