Read item weight, value and base name through the bridge

Consumers of the legacy ItemTemplate item_wt, item_value and
item_base_name now read getItemWt(), getItemValue() and
getItemBaseName() on template.cacheTemplate.

Parity (offline, scripts/p14.py, 7586 templates): 0 differences in
item_wt, item_value and item_base_name. No value changes expected.

JSON-Refactor-Plan Task 1.4.

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

src/engine/net/client/handlers/AddItemToTradeWindowMsgHandler.java

@@ -78,7 +78,7 @@ public class AddItemToTradeWindowMsgHandler extends AbstractClientMsgHandler {
         if (!item.validForInventory(source.getClientConnection(), source, source.charItemManager))
             return false;
 
-        if (!tradingWith.hasRoomTrade(item.template.item_wt)) {
+        if (!tradingWith.hasRoomTrade(item.template.cacheTemplate.getItemWt())) {
             dispatch = Dispatch.borrow(source, msg);
             DispatchManager.dispatchMsgDispatch(dispatch, mbEnums.DispatchChannel.PRIMARY);
             return false;