feat(tasks): add quick-status button to kanban cards (#24)

Adds a small button on each kanban card that cycles the task status
(open → in_progress → done → open) without requiring drag-and-drop.
Useful for touch devices and kiosk browsers (e.g. Fully Kiosk Browser)
where drag-and-drop is unavailable. All four locales updated.

public/locales/de.json

@@ -142,6 +142,9 @@
     "kanbanOpen": "Offen",
     "kanbanInProgress": "In Bearbeitung",
     "kanbanDone": "Erledigt",
+    "kanbanMoveToInProgress": "In Bearbeitung setzen",
+    "kanbanMoveToDone": "Als erledigt markieren",
+    "kanbanMoveToOpen": "Erneut öffnen",
     "recurring": "Wiederkehrend",
     "listView": "Listenansicht",
     "kanbanView": "Kanban-Ansicht"