gui_client: fix dashboard dropping plain-value fields

DashboardTab.update() had no else-branch for non-dict, non-physical
values, so string fields like charging.state/type, connectivity.state,
vehicle.state and numeric fields like position.lat/lon were silently
skipped.  Mirrors the existing else-branch in _add_fields().

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

client/gui_client.py

@@ -342,6 +342,10 @@ class DashboardTab(QWidget):
                     obj_item.setFont(0, bold)
                     self._add_fields(obj_item, fields, f"{domain}/{obj_name}")
                     d_item.addChild(obj_item)
+                else:
+                    item = QTreeWidgetItem([obj_name, str(fields), ""])
+                    item.setTextAlignment(1, Qt.AlignRight | Qt.AlignVCenter)
+                    d_item.addChild(item)
             self._tree.addTopLevelItem(d_item)
 
         self._tree.expandAll()