Playerbot: log the real reason a quest-source item grant is rejected

'bag full' was misleading — with free slots AddItem can still return false
via CanStoreNewItem/StoreNewItem rejection (bound-item guard etc). Include the
CanStoreNewItem result (ir), noSpace, actual free backpack slots, and current
item count in the failure log so the rejection reason is visible.

src/modules/PlayerbotV2/PlayerbotV2.cpp

@@ -2992,14 +2992,28 @@ static bool GiveQuestItem(Player* bot, uint32 itemId, uint32 count)
         if (proto && proto->GetStartQuest() > 0 &&
             bot->GetItemCount(itemId, false) == 0)
         {
+            ItemPosCountVec dest;
+            uint32 noSpace = 0;
+            InventoryResult const ir =
+                bot->CanStoreNewItem(NULL_BAG, NULL_SLOT, dest, itemId, 1, &noSpace);
             if (bot->AddItem(itemId, 1))
+            {
                 TC_LOG_ERROR("playerbot.v2",
                     "[QuestItemCopy] OK {} +1x source item={} (starts quest {})",
                     bot->GetName(), itemId, proto->GetStartQuest());
+            }
             else
+            {
+                uint32 freeBackpack = 0;
+                for (uint8 s = INVENTORY_SLOT_ITEM_START; s < INVENTORY_SLOT_ITEM_END; ++s)
+                    if (!bot->GetItemByPos(INVENTORY_SLOT_BAG_0, s))
+                        ++freeBackpack;
                 TC_LOG_ERROR("playerbot.v2",
-                    "[QuestItemCopy] FAIL {} source item={} (bag full)",
+                    "[QuestItemCopy] FAIL {} source item={} ir={} noSpace={} "
-                    bot->GetName(), itemId);
+                    "freeBackpack={} have={} (AddItem rejected — not plain fullness)",
+                    bot->GetName(), itemId, uint32(ir), noSpace, freeBackpack,
+                    bot->GetItemCount(itemId, false));
+            }
         }
         return true;
     }