refactor(combat): replace ac_penalty with effect system

src/pf1e_simulator/effects.py

@@ -18,7 +18,7 @@ from dataclasses import dataclass
 from typing import TYPE_CHECKING, Literal
 
 if TYPE_CHECKING:
-    from collections.abc import Sequence
+    from collections.abc import Iterable
 
 BonusType = Literal[
     "",               # untyped — stacks with everything
@@ -65,7 +65,7 @@ class StatModifier:
     weapon_filter: str | None = None
 
 
-def resolve_modifiers(modifiers: Sequence[StatModifier]) -> int:
+def resolve_modifiers(modifiers: Iterable[StatModifier]) -> int:
     """Sum stat modifiers applying PF1e stacking rules.
 
     Stacking bonus types (dodge, racial, trait, untyped) all sum together.