fix(theme): reduce tree item horizontal padding to prevent truncation

QTreeView::item had padding: 4px on all sides, eating 8px of
horizontal space per item. Combined with icon decorations and
indentation this caused excessive middle-elide truncation in the
model tree. Change to padding: 2px 0px (vertical only).

src/Gui/PreferencePacks/KindredCreate/KindredCreate.qss

@@ -759,7 +759,7 @@ QTreeView {
 }
 
 QTreeView::item {
-    padding: 4px;
+    padding: 2px 0px;
     border-radius: 2px;
 }
 

src/Gui/Stylesheets/KindredCreate.qss

@@ -759,7 +759,7 @@ QTreeView {
 }
 
 QTreeView::item {
-    padding: 4px;
+    padding: 2px 0px;
     border-radius: 2px;
 }