fix: bag main functionality

UI/BagFrame.lua

@@ -1608,11 +1608,10 @@ function Guda_BagFrame_HighlightBagButton(bagID)
     if bagID == -2 then
         -- Keyring button
         buttonName = "Guda_BagFrame_Toolbar_KeyringButton"
-    elseif bagID >= 1 and bagID <= 4 then
-        -- Bag buttons 1-4
+    elseif bagID >= 0 and bagID <= 4 then
+        -- Bag buttons 0-4 (0 is backpack)
         buttonName = "Guda_BagFrame_Toolbar_BagSlot" .. bagID
     else
-        -- Bag 0 (backpack) has no button in the toolbar
         return
     end
 
@@ -1625,8 +1624,8 @@ end
 
 -- Clear bag button highlighting
 function Guda_BagFrame_ClearBagButtonHighlight()
-    -- Clear highlight from all bag buttons (1-4)
-    for bagID = 1, 4 do
+    -- Clear highlight from all bag buttons (0-4)
+    for bagID = 0, 4 do
         local buttonName = "Guda_BagFrame_Toolbar_BagSlot" .. bagID
         local button = getglobal(buttonName)
         if button then

UI/BagFrame.xml

@@ -273,8 +273,8 @@
                 </Scripts>
 
                 <Frames>
-                    <!-- Bag Slot 1 -->
-                    <Button name="$parent_BagSlot1" inherits="ItemButtonTemplate" movable="true">
+                    <!-- Main Bag (Backpack) Slot 0 -->
+                    <Button name="$parent_BagSlot0" inherits="ItemButtonTemplate">
                         <Size>
                             <AbsDimension x="24" y="24"/>
                         </Size>
@@ -285,6 +285,39 @@
                                 </Offset>
                             </Anchor>
                         </Anchors>
+                        <Scripts>
+                            <OnLoad>
+                                Guda_BagSlot_OnLoad(this, 0)
+                            </OnLoad>
+                            <OnClick>
+                                Guda_BagSlot_OnClick(this, 0)
+                            </OnClick>
+                            <OnEnter>
+                                Guda_BagSlot_OnEnter(this, 0)
+                                Guda_BagFrame_HighlightBagSlots(0)
+                            </OnEnter>
+                            <OnLeave>
+                                GameTooltip:Hide()
+                                Guda_BagFrame_ClearHighlightedSlots()
+                            </OnLeave>
+                            <OnEvent>
+                                Guda_BagSlot_OnEvent(this, event, arg1)
+                            </OnEvent>
+                        </Scripts>
+                    </Button>
+
+                    <!-- Bag Slot 1 -->
+                    <Button name="$parent_BagSlot1" inherits="ItemButtonTemplate" movable="true">
+                        <Size>
+                            <AbsDimension x="24" y="24"/>
+                        </Size>
+                        <Anchors>
+                            <Anchor point="LEFT" relativePoint="RIGHT" relativeTo="$parent_BagSlot0">
+                                <Offset>
+                                    <AbsDimension x="2" y="0"/>
+                                </Offset>
+                            </Anchor>
+                        </Anchors>
                         <Scripts>
                             <OnLoad>
                                 this:RegisterForDrag("LeftButton")