Fix online mode combat and implement server inventory sync

Right-click now attacks hostile NPCs (npcFlags==0) and interacts with
friendly ones in online mode. Parse UNIT_FIELD_FLAGS (59) and
UNIT_NPC_FLAGS (82) from update packets. Stop auto-attack when target
dies or despawns. Add CMSG_ITEM_QUERY_SINGLE/SMSG_ITEM_QUERY_SINGLE_RESPONSE
to populate inventory from server item objects and player slot fields.

include/game/entity.hpp

@@ -151,6 +151,17 @@ public:
     uint32_t getDisplayId() const { return displayId; }
     void setDisplayId(uint32_t id) { displayId = id; }
 
+    // Unit flags (UNIT_FIELD_FLAGS, index 59)
+    uint32_t getUnitFlags() const { return unitFlags; }
+    void setUnitFlags(uint32_t f) { unitFlags = f; }
+
+    // NPC flags (UNIT_NPC_FLAGS, index 82)
+    uint32_t getNpcFlags() const { return npcFlags; }
+    void setNpcFlags(uint32_t f) { npcFlags = f; }
+
+    // Returns true if NPC has interaction flags (gossip/vendor/quest/trainer)
+    bool isInteractable() const { return npcFlags != 0; }
+
 protected:
     std::string name;
     uint32_t health = 0;
@@ -161,6 +172,8 @@ protected:
     uint32_t level = 1;
     uint32_t entry = 0;
     uint32_t displayId = 0;
+    uint32_t unitFlags = 0;
+    uint32_t npcFlags = 0;
 };
 
 /**

include/game/game_handler.hpp

@@ -410,6 +410,9 @@ private:
     // ---- Phase 1 handlers ----
     void handleNameQueryResponse(network::Packet& packet);
     void handleCreatureQueryResponse(network::Packet& packet);
+    void handleItemQueryResponse(network::Packet& packet);
+    void queryItemInfo(uint32_t entry, uint64_t guid);
+    void rebuildOnlineInventory();
 
     // ---- Phase 2 handlers ----
     void handleAttackStart(network::Packet& packet);
@@ -535,6 +538,17 @@ private:
     std::unordered_map<uint32_t, CreatureQueryResponseData> creatureInfoCache;
     std::unordered_set<uint32_t> pendingCreatureQueries;
 
+    // ---- Online item tracking ----
+    struct OnlineItemInfo {
+        uint32_t entry = 0;
+        uint32_t stackCount = 1;
+    };
+    std::unordered_map<uint64_t, OnlineItemInfo> onlineItems_;
+    std::unordered_map<uint32_t, ItemQueryResponseData> itemInfoCache_;
+    std::unordered_set<uint32_t> pendingItemQueries_;
+    std::array<uint64_t, 23> equipSlotGuids_{};
+    std::array<uint64_t, 16> backpackSlotGuids_{};
+
     // ---- Phase 2: Combat ----
     bool autoAttacking = false;
     uint64_t autoAttackTarget = 0;

include/game/opcodes.hpp

@@ -139,6 +139,8 @@ enum class Opcode : uint16_t {
     SMSG_BUY_FAILED                  = 0x1A5,
 
     // ---- Phase 5: Item/Equip ----
+    CMSG_ITEM_QUERY_SINGLE           = 0x056,
+    SMSG_ITEM_QUERY_SINGLE_RESPONSE  = 0x058,
     CMSG_AUTOEQUIP_ITEM              = 0x10A,
     SMSG_INVENTORY_CHANGE_FAILURE    = 0x112,
 };

include/game/world_packets.hpp

@@ -715,6 +715,41 @@ public:
     static bool parse(network::Packet& packet, CreatureQueryResponseData& data);
 };
 
+// ============================================================
+// Item Query
+// ============================================================
+
+/** CMSG_ITEM_QUERY_SINGLE packet builder */
+class ItemQueryPacket {
+public:
+    static network::Packet build(uint32_t entry, uint64_t guid);
+};
+
+/** SMSG_ITEM_QUERY_SINGLE_RESPONSE data */
+struct ItemQueryResponseData {
+    uint32_t entry = 0;
+    std::string name;
+    uint32_t displayInfoId = 0;
+    uint32_t quality = 0;
+    uint32_t inventoryType = 0;
+    int32_t maxStack = 1;
+    uint32_t containerSlots = 0;
+    int32_t armor = 0;
+    int32_t stamina = 0;
+    int32_t strength = 0;
+    int32_t agility = 0;
+    int32_t intellect = 0;
+    int32_t spirit = 0;
+    std::string subclassName;
+    bool valid = false;
+};
+
+/** SMSG_ITEM_QUERY_SINGLE_RESPONSE parser */
+class ItemQueryResponseParser {
+public:
+    static bool parse(network::Packet& packet, ItemQueryResponseData& data);
+};
+
 // ============================================================
 // Phase 2: Combat Core
 // ============================================================