Rename legacy PowerGrant to PowerGrantedTrains

Ends the name clash with the parser's engine.parsers.objects.PowerGrant.
It no longer extends AbstractGameObject: it was never cached or sent as a
game object, and the renamed class has no GameObjectType entry.

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

src/engine/objects/CharacterPower.java

@@ -334,7 +334,7 @@ public class CharacterPower extends AbstractGameObject {
             //					return pc.getBonuses().getByte("gt." + this.power.getToken());
             //			} else
             //				return pc.getBonuses().getByte("gt." + this.power.getToken());
-            return PowerGrant.getGrantedTrains(this.power.getToken(), pc);
+            return PowerGrantedTrains.getGrantedTrains(this.power.getToken(), pc);
         } else
             return 0;
     }