hunt-set: 小狩猎套装礼包 is free in the item mall

CShopEx::Buy rejected price 0 as a hack; allow it like CShop::Buy already does.
Rebuilt and deployed game on 203; buying the box for 0 verified.

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

tools/server/hunt-set/server.patch

@@ -31,3 +31,15 @@
  			{ "get_vnum",		item_get_vnum		},
  			{ "has_flag",		item_has_flag		},
  			{ "get_value",		item_get_value		},
+--- a/server/game/src/shopEx.cpp
++++ b/server/game/src/shopEx.cpp
+@@ -133,7 +133,8 @@
+ 	TShopTableEx& shopTab = m_vec_shopTabs[tabIdx];
+ 	TShopItemTable& r_item = shopTab.items[slotPos];
+ 
+-	if (r_item.price <= 0)
++	// if (r_item.price <= 0)
++	if (r_item.price < 0) // Fix, as in CShop::Buy: a free item (price 0) can be bought
+ 	{
+ 		LogManager::instance().HackLog("SHOP_BUY_GOLD_OVERFLOW", ch);
+ 		return SHOP_SUBHEADER_GC_NOT_ENOUGH_MONEY;