feat(ugc): placed models from the UGC server without 3D services

A placed model's client (1.10.64, UGCUSE3DSERVICES=7:0) always loads its
blueprint's NIF and HKX (its BlueprintComponent sets renderUserGen and
physicsUserGen itself) and its LXFML, asks the world for each file's
manifest first and waits for the answer with no timeout.

With ugc_manifest=1 and the new ugc_manifest_models=1 (default 0) the world:
- leaves the models whose mesh the UGC server made out of the LXFML it
  sends when a property loads,
- answers their NIF with the UGC server's checksum, their LXFML with the
  stored LXFML's (worked out once and kept) and their HKX as not known,
- sends a model that isn't made its LXFML (once for the three requests),
  so the client builds it itself and no model is left waiting.

When the UGC server writes a model's mesh with a new checksum it sends
UGC_MODELS_MADE (a new master message, appended) to the master, which
passes it to every world; a world with that model placed sends its
players the new NIF checksum and NotifyClientUGCModelReady (game message
909, the blueprint id), so clients switch to the served mesh.

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

dCommon/dEnums/MessageType/Master.h

@@ -66,5 +66,9 @@ namespace MessageType {
 
 		// Any server -> master -> dashboard: traffic counters of the last few seconds (see ServerTraffic.h)
 		SERVER_TRAFFIC,
+
+		// UGC server -> master -> every world: player models whose mesh (model.nif) was just made or made again (see
+		// UgcModelsMade.h), so worlds showing them tell their clients (NotifyClientUGCModelReady)
+		UGC_MODELS_MADE,
 	};
 }