Send parent buildings before their furniture in LOADSTRUCTURE

The structure list comes from a HashSet, so its order was never fixed:
positive UIDs happened to put a parent before its children, negative
static IDs put the children first. Live recordings send the parent first
in all 2,365 parent/child pairs within one record (none the other way);
the citadel-test recording had all 616 children first, and the Citadel of
War's upper-floor table and chairs (CZONE Y 27, sent correctly) showed on
the ground floor. Top-level buildings are now written first, then children.

Value changes: record order only; every field is unchanged.

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

src/engine/net/client/msg/LoadStructureMsg.java

@@ -66,9 +66,16 @@ public class LoadStructureMsg extends ClientNetMsg {
 
         writer.putInt(this.structureList.size());
 
-        for (Building building : this.structureList) {
-            Building._serializeForClientMsg(building, writer);
-        }
+        // Parents before children, as live servers sent them; a child sent first loses its height on the client.
+
+        for (Building building : this.structureList)
+            if (building.parentBuildingID == 0)
+                Building._serializeForClientMsg(building, writer);
+
+        for (Building building : this.structureList)
+            if (building.parentBuildingID != 0)
+                Building._serializeForClientMsg(building, writer);
+
         writer.putInt(0);
     }