Fix equipment textures: correct DBC field indices and stop texture cycling

Binary ItemDisplayInfo.dbc has 23 fields with texture components at
14-21, not 15-22. The previous "fix" shifted all fields by +1 which
read wrong columns and broke both player and NPC equipment rendering.

Also fix local player texture cycling: rebuildOnlineInventory() was
called on every item query response (including for other players),
unconditionally setting onlineEquipDirty_ which triggered redundant
texture recompositing. Now tracks previous equipment displayInfoIds
and only sets dirty when they actually change.

Unified all 3 equipment texture code paths (local player, other
players, NPCs) to use the DBC layout system with correct field 14
base index.

include/game/game_handler.hpp

@@ -1134,6 +1134,7 @@ private:
     int packSlotBase_ = -1;
     std::map<uint16_t, uint32_t> lastPlayerFields_;
     bool onlineEquipDirty_ = false;
+    std::array<uint32_t, 19> lastEquipDisplayIds_{};
 
     // Visible equipment for other players: detect the update-field layout (base + stride)
     // using the local player's own equipped items, then decode other players by index.