game,warden,assets: fix unknown player names, warden heap overlap, and Vanilla Item.dbc

- game: clear pendingNameQueries on player out-of-range and DESTROY_OBJECT so
  re-entering players get a fresh name query instead of being silently skipped
- game: add 5s periodic name resync scan that re-queries players with empty names
  and no pending query, recovering from dropped CMSG_NAME_QUERY responses
- warden: fix UC_ERR_MAP by moving HEAP_BASE from 0x200000 to 0x20000000; the old
  heap [0x200000, 0x1200000) overlapped the module at 0x400000, causing Unicorn to
  reject the heap mapping and abort emulator initialisation
- warden: add early overlap check between module and heap regions to catch future
  layout bugs at init time
- assets: add loadDBCOptional() which logs at DEBUG level when a DBC is absent,
  for files that are not distributed on all expansions
- assets: use loadDBCOptional for Item.dbc (absent on Vanilla 1.12 clients) and
  fall back to server-sent itemInfoCache displayInfoId for NPC weapon resolution

include/pipeline/asset_manager.hpp

@@ -66,6 +66,14 @@ public:
      */
     std::shared_ptr<DBCFile> loadDBC(const std::string& name);
 
+    /**
+     * Load a DBC file that is optional (not all expansions ship it).
+     * Returns nullptr quietly (debug-level log only) when the file is absent.
+     * @param name DBC file name (e.g., "Item.dbc")
+     * @return Loaded DBC file, or nullptr if not available
+     */
+    std::shared_ptr<DBCFile> loadDBCOptional(const std::string& name);
+
     /**
      * Get a cached DBC file
      * @param name DBC file name