feat: implement item durability tracking and vendor repair

- Add ITEM_FIELD_DURABILITY (60) and ITEM_FIELD_MAXDURABILITY (61) to
  update_field_table.hpp enum and wotlk/update_fields.json
- Add curDurability/maxDurability to OnlineItemInfo and ItemDef structs
- Parse durability fields in OBJECT_CREATE and OBJECT_VALUES handlers;
  preserve existing values on partial updates (fixes stale durability
  being reset to 0 on stack-count-only updates)
- Propagate durability to ItemDef in all 5 rebuildOnlineInventory() paths
- Implement GameHandler::repairItem() and repairAll() via CMSG_REPAIR_ITEM
  (itemGuid=0 repairs all equipped items per WotLK protocol)
- Add canRepair flag to ListInventoryData; set it when player selects
  GOSSIP_OPTION_ARMORER in gossip window
- Show "Repair All" button in vendor window header when canRepair=true
- Display color-coded durability in item tooltip (green >50%, yellow
  >25%, red <=25%)

include/game/game_handler.hpp

@@ -1258,6 +1258,8 @@ public:
         uint32_t count = 1;
     };
     void buyBackItem(uint32_t buybackSlot);
+    void repairItem(uint64_t vendorGuid, uint64_t itemGuid);
+    void repairAll(uint64_t vendorGuid, bool useGuildBank = false);
     const std::deque<BuybackItem>& getBuybackItems() const { return buybackItems_; }
     void autoEquipItemBySlot(int backpackIndex);
     void autoEquipItemInBag(int bagIndex, int slotIndex);
@@ -1269,6 +1271,7 @@ public:
     void useItemById(uint32_t itemId);
     bool isVendorWindowOpen() const { return vendorWindowOpen; }
     const ListInventoryData& getVendorItems() const { return currentVendorItems; }
+    void setVendorCanRepair(bool v) { currentVendorItems.canRepair = v; }
 
     // Mail
     bool isMailboxOpen() const { return mailboxOpen_; }
@@ -1831,6 +1834,8 @@ private:
     struct OnlineItemInfo {
         uint32_t entry = 0;
         uint32_t stackCount = 1;
+        uint32_t curDurability = 0;
+        uint32_t maxDurability = 0;
     };
     std::unordered_map<uint64_t, OnlineItemInfo> onlineItems_;
     std::unordered_map<uint32_t, ItemQueryResponseData> itemInfoCache_;

include/game/inventory.hpp

@@ -46,6 +46,8 @@ struct ItemDef {
     int32_t spirit = 0;
     uint32_t displayInfoId = 0;
     uint32_t sellPrice = 0;
+    uint32_t curDurability = 0;
+    uint32_t maxDurability = 0;
 };
 
 struct ItemSlot {

include/game/update_field_table.hpp

@@ -56,6 +56,8 @@ enum class UF : uint16_t {
 
     // Item fields
     ITEM_FIELD_STACK_COUNT,
+    ITEM_FIELD_DURABILITY,
+    ITEM_FIELD_MAXDURABILITY,
 
     // Container fields
     CONTAINER_FIELD_NUM_SLOTS,

include/game/world_packets.hpp

@@ -2179,6 +2179,7 @@ struct VendorItem {
 struct ListInventoryData {
     uint64_t vendorGuid = 0;
     std::vector<VendorItem> items;
+    bool canRepair = false;  // Set when vendor was opened via GOSSIP_OPTION_ARMORER
 
     bool isValid() const { return true; }
 };