Keep siege engine target when a new player loads it

InterestManager cleared the combat target of every live mob loaded for
a new player, so a siege engine firing at a wall dropped its target
whenever someone entered load range. Siege engines now keep it.

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

src/engine/InterestManagement/InterestManager.java

@@ -468,7 +468,12 @@ public enum InterestManager implements Runnable {
                         continue;
 
                     awonpc.playerAgroMap.put(player.getObjectUUID(), 0f);
-                    ((Mob) awonpc).setCombatTarget(null);
+
+                    // siege engines keep firing at their target when a new player loads them
+
+                    if (!awonpc.isSiege())
+                        ((Mob) awonpc).setCombatTarget(null);
+
                     lcm = new LoadCharacterMsg(awonpc, PlayerCharacter.hideNonAscii());
 
                 } else if ((awo.getObjectTypeMask() & MBServerStatics.MASK_NPC) != 0) {