Bridge legacy ItemTemplate to its cache template

Each engine.objects.ItemTemplate gets a cacheTemplate field, filled by
linkCacheTemplates() right after CObjectIndex.build() on both servers,
so consumers can move to CObjectTemplate one field at a time.

ParityCheck gains a static_item_templates comparator: a null bridge is
reported as missing in json, and obj_name and item_type are compared
through the interface to catch a wrong folder pick.

Import convention until the legacy class is removed (Task 1.8): the
legacy engine.objects.ItemTemplate keeps the plain import; the cache
class is always written engine.parsers.objects.ItemTemplate. Migrated
consumers should depend on CObjectTemplate instead.

JSON-Refactor-Plan Task 1.1. No consumers change; no values change.

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

src/engine/server/login/LoginServer.java

@@ -318,6 +318,9 @@ public class LoginServer {
         Logger.info("Indexing Cache Templates");
         CObjectIndex.build();
 
+        Logger.info("Linking Item Templates to Cache Templates");
+        ItemTemplate.linkCacheTemplates();
+
         Logger.info("Initializing Network");
         Network.init();