Key MobBase on its ID and stop reading loadID

Every static_npc_mobbase row has ID = loadID since 3.6 dropped the
server-made rows, so the race rune and rune effects are looked up by ID and
the loaders no longer filter on loadID. No value change (dev: 2375 of 2375
rows have ID = loadID). Mob.loadID and NPC.loadID are unchanged.

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

src/engine/objects/NPC.java

@@ -236,7 +236,7 @@ public class NPC extends AbstractCharacter {
         writer.putInt(0);
 
         if (npc.mobBase != null)
-            writer.putInt(npc.mobBase.getLoadID());
+            writer.putInt(npc.mobBase.getObjectUUID());
         else
             writer.putInt(2011);