refs #373: Improve and homogenize icon sizing when items enter invent…

…ory.

- **fix**: Assign unique names to the **Up** and **Down** icons in the
  base **InventoryGrid** component.

addons/popochiu/engine/objects/gui/components/inventory_grid/inventory_grid.tscn

@@ -54,6 +54,7 @@ layout_mode = 2
 theme_override_constants/separation = 0
 
 [node name="Up" type="TextureButton" parent="ScrollButtons"]
+unique_name_in_owner = true
 texture_filter = 1
 layout_mode = 2
 size_flags_vertical = 3
@@ -64,6 +65,7 @@ texture_disabled = SubResource("AtlasTexture_73nr4")
 stretch_mode = 3
 
 [node name="Down" type="TextureButton" parent="ScrollButtons"]
+unique_name_in_owner = true
 texture_filter = 1
 layout_mode = 2
 size_flags_vertical = 3

addons/popochiu/engine/objects/gui/templates/simple_click/components/simple_click_bar/simple_click_bar.gd

@@ -156,9 +156,9 @@ func _on_tween_finished() -> void:
 func _add_item(item: PopochiuInventoryItem, animate := true) -> void:
 	box.add_child(item)
 
-	item.custom_minimum_size.x = box.size.y
 	item.size_flags_horizontal = Control.SIZE_SHRINK_BEGIN
 	item.size_flags_vertical = Control.SIZE_FILL
+	item.expand_mode = TextureRect.EXPAND_FIT_WIDTH
 
 	item.selected.connect(_change_cursor)