Fixes #11

- Fix dashboard draggin: introduced sophistaced drag handle
- Fix disappearing of charts when dragged inside a dashboard widget

src/main/resources/vaadin-i18n/translations_en.properties

@@ -24,7 +24,7 @@ card.registration=Registration
 card.employees=Employees
 card.gridstackHint=How it works
 
-gridstack.hint=Drag cards by their header to move them, resize them from the bottom right corner. The layout is stored in your browser and restored on your next visit.
+gridstack.hint=Move cards with the grip in their top right corner, resize them from the bottom right corner. The layout is stored in your browser and restored on your next visit.
 gridstack.addWidget=Add widget
 gridstack.removeWidget=Remove last
 gridstack.reset=Reset layout
@@ -32,6 +32,7 @@ gridstack.status=Layout changed – {0} widgets
 gridstack.statusInitial=Layout unchanged
 gridstack.widget=Widget {0}
 gridstack.widgetText=Freely placeable card.
+gridstack.dragHandle=Move
 
 chart.revenueSeries=Revenue 2026
 chart.pointClick=Series {0}, point {1}