fix: add a per-widget action menu (#27)

A GridStackItem now carries an overflow menu next to the grip and the
close button: refresh, maximize, duplicate, remove. Maximize and remove
are handled by the item itself; refresh and duplicate are only reported,
since what they mean depends on the widget.

Maximizing only sets a class — the item's gs-* attributes and its
gridstack node are untouched, so restoring is by definition the position
it had.

The menu sits outside the drag-handle selector, like the close button, so
opening it never starts a drag; a Playwright test drags it to prove it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0124BiJikbhbiEsNfJxdWM69

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

@@ -22,7 +22,7 @@ card.registration=Registration
 card.employees=Employees
 card.gridstackHint=How it works
 
-gridstack.hint=Move cards with the grip in their top right corner, resize them from the bottom right corner, close them with the X in the top 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, close them with the X in the top right corner. More actions – refresh, maximize, duplicate – live in the menu next to it. The layout is stored in your browser and restored on your next visit.
 gridstack.addWidget=Add widget
 gridstack.reset=Reset layout
 gridstack.status=Layout changed – {0} widgets
@@ -30,6 +30,12 @@ gridstack.statusInitial=Layout unchanged
 gridstack.pickerTitle=Choose a widget
 gridstack.dragHandle=Move
 gridstack.close=Close
+gridstack.actions=Actions
+gridstack.refresh=Refresh
+gridstack.maximize=Maximize
+gridstack.restore=Restore
+gridstack.duplicate=Duplicate
+gridstack.remove=Remove
 
 filter.period=Period
 filter.period.month=Month