fix(rules): apply AC penalties to CMD

PF1e (SRD Combat Maneuvers): "Any penalties to a creature's AC also
apply to its CMD." _maneuver_cmd now folds negative AC modifiers into the
sum regardless of bonus type (grappled -2, other untyped penalties), and —
a maneuver being a melee attack roll — the prone -4 melee AC penalty.
Positive modifiers keep the eight SRD-listed types. The test that pinned
the old ignore-penalties convention is updated; README documents the rule.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/pf1e_simulator/combat.py

@@ -4192,11 +4192,20 @@ class CombatEngine:
         dex_mod = target.combatant.abilities.dex_mod
         if self.has_condition_flag(target, "denies_dex_to_ac"):
             dex_mod = min(0, dex_mod)
-        ac_bonuses = resolve_modifiers(
+        # PF1e (SRD Combat Maneuvers): "Any penalties to a creature's AC also
+        # apply to its CMD." — negative AC modifiers ride the CMD whatever
+        # their bonus type; only positive ones are restricted to the eight
+        # SRD-listed types.
+        ac_mods = [
             m
             for m in self._stat_modifiers(target, "ac")
-            if m.bonus_type in _CMD_AC_BONUS_TYPES
-        )
+            if m.bonus_type in _CMD_AC_BONUS_TYPES or m.value < 0
+        ]
+        # A combat maneuver is a melee attack roll (SRD: "Combat maneuvers are
+        # attack rolls"), so the prone defender's -4 melee AC penalty applies.
+        if self._has_condition_named(target, "prone"):
+            ac_mods.append(StatModifier(target="ac", value=-4))
+        ac_bonuses = resolve_modifiers(ac_mods)
         # defensive_ac_bonus (total defense / fight defensively) is a dodge
         # bonus and aid_ac_bonus a circumstance bonus to AC — both types the
         # SRD lets a creature add to its CMD.