Pull siege engine aggro on damage only

A siege engine switches to whoever damages it, player or pet, even when
it already has a target. Pre-roll melee retaliation, harmful-power
direct aggro (which also fires on misses) and Taunt no longer change a
siege engine's target. The attack timer is untouched, so a switched
engine still waits for its next cycle before firing.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/engine/powers/poweractions/ApplyEffectPowerAction.java

@@ -246,7 +246,9 @@ public class ApplyEffectPowerAction extends AbstractPowerAction {
 
             if (this.effectID.equals("TAUNT")) {
 
-                if (awo != null && awo.getObjectType() == GameObjectType.Mob) {
+                // siege engines only switch targets on damage, see AbstractCharacter.modifyHealth
+
+                if (awo != null && awo.getObjectType() == GameObjectType.Mob && !((Mob) awo).isSiege()) {
                     ((Mob) awo).setCombatTarget(source);
                     ChatSystemMsg msg = ChatManager.CombatInfo(source, awo);
                     DispatchManager.sendToAllInRange(source, msg);