feat: add undo action for checking items

lib/messages.i18n.dart

@@ -707,6 +707,16 @@ class ChecklistsMessages {
   /// ```
   String get moveFailed => """Failed to move item.""";
 
+  /// ```dart
+  /// "Item marked as done"
+  /// ```
+  String get itemMarkedDone => """Item marked as done""";
+
+  /// ```dart
+  /// "Undo"
+  /// ```
+  String get undo => """Undo""";
+
   /// ```dart
   /// "New list"
   /// ```
@@ -1574,6 +1584,8 @@ Please complete login in your browser.""",
   """checklists.removeItem""": """Remove item""",
   """checklists.moveItem""": """Move to list""",
   """checklists.moveFailed""": """Failed to move item.""",
+  """checklists.itemMarkedDone""": """Item marked as done""",
+  """checklists.undo""": """Undo""",
   """checklists.createList""": """New list""",
   """checklists.listName""": """List name""",
   """checklists.listDescription""": """Description (optional)""",

lib/messages.i18n.yaml

@@ -129,6 +129,8 @@ checklists:
   removeItem: Remove item
   moveItem: Move to list
   moveFailed: Failed to move item.
+  itemMarkedDone: Item marked as done
+  undo: Undo
   createList: New list
   listName: List name
   listDescription: Description (optional)

lib/messages_de.i18n.dart

@@ -713,6 +713,16 @@ class ChecklistsMessagesDe extends ChecklistsMessages {
   /// ```
   String get moveFailed => """Eintrag konnte nicht verschoben werden.""";
 
+  /// ```dart
+  /// "Eintrag als erledigt markiert"
+  /// ```
+  String get itemMarkedDone => """Eintrag als erledigt markiert""";
+
+  /// ```dart
+  /// "Rückgängig"
+  /// ```
+  String get undo => """Rückgängig""";
+
   /// ```dart
   /// "Neue Liste"
   /// ```
@@ -1595,6 +1605,8 @@ Bitte melde dich in deinem Browser an.""",
   """checklists.removeItem""": """Eintrag entfernen""",
   """checklists.moveItem""": """In Liste verschieben""",
   """checklists.moveFailed""": """Eintrag konnte nicht verschoben werden.""",
+  """checklists.itemMarkedDone""": """Eintrag als erledigt markiert""",
+  """checklists.undo""": """Rückgängig""",
   """checklists.createList""": """Neue Liste""",
   """checklists.listName""": """Listenname""",
   """checklists.listDescription""": """Beschreibung (optional)""",

lib/messages_de.i18n.yaml

@@ -129,6 +129,8 @@ checklists:
   removeItem: Eintrag entfernen
   moveItem: In Liste verschieben
   moveFailed: Eintrag konnte nicht verschoben werden.
+  itemMarkedDone: Eintrag als erledigt markiert
+  undo: "Rückgängig"
   createList: Neue Liste
   listName: Listenname
   listDescription: Beschreibung (optional)

lib/messages_es.i18n.dart

@@ -711,6 +711,16 @@ class ChecklistsMessagesEs extends ChecklistsMessages {
   /// ```
   String get moveFailed => """No se pudo mover el artículo.""";
 
+  /// ```dart
+  /// "Artículo marcado como hecho"
+  /// ```
+  String get itemMarkedDone => """Artículo marcado como hecho""";
+
+  /// ```dart
+  /// "Deshacer"
+  /// ```
+  String get undo => """Deshacer""";
+
   /// ```dart
   /// "Nueva lista"
   /// ```
@@ -1587,6 +1597,8 @@ Por favor, completa el inicio de sesión en tu navegador.""",
   """checklists.removeItem""": """Eliminar artículo""",
   """checklists.moveItem""": """Mover a lista""",
   """checklists.moveFailed""": """No se pudo mover el artículo.""",
+  """checklists.itemMarkedDone""": """Artículo marcado como hecho""",
+  """checklists.undo""": """Deshacer""",
   """checklists.createList""": """Nueva lista""",
   """checklists.listName""": """Nombre de la lista""",
   """checklists.listDescription""": """Descripción (opcional)""",

lib/messages_es.i18n.yaml

@@ -129,6 +129,8 @@ checklists:
   removeItem: "Eliminar artículo"
   moveItem: Mover a lista
   moveFailed: "No se pudo mover el artículo."
+  itemMarkedDone: "Artículo marcado como hecho"
+  undo: Deshacer
   createList: Nueva lista
   listName: Nombre de la lista
   listDescription: "Descripción (opcional)"

lib/messages_fr.i18n.dart

@@ -714,6 +714,16 @@ class ChecklistsMessagesFr extends ChecklistsMessages {
   /// ```
   String get moveFailed => """Impossible de déplacer l'article.""";
 
+  /// ```dart
+  /// "Article marqué comme fait"
+  /// ```
+  String get itemMarkedDone => """Article marqué comme fait""";
+
+  /// ```dart
+  /// "Annuler"
+  /// ```
+  String get undo => """Annuler""";
+
   /// ```dart
   /// "Nouvelle liste"
   /// ```
@@ -1592,6 +1602,8 @@ Veuillez terminer la connexion dans votre navigateur.""",
   """checklists.removeItem""": """Supprimer l'article""",
   """checklists.moveItem""": """Déplacer vers une liste""",
   """checklists.moveFailed""": """Impossible de déplacer l'article.""",
+  """checklists.itemMarkedDone""": """Article marqué comme fait""",
+  """checklists.undo""": """Annuler""",
   """checklists.createList""": """Nouvelle liste""",
   """checklists.listName""": """Nom de la liste""",
   """checklists.listDescription""": """Description (facultatif)""",

lib/messages_fr.i18n.yaml

@@ -129,6 +129,8 @@ checklists:
   removeItem: Supprimer l'article
   moveItem: "Déplacer vers une liste"
   moveFailed: "Impossible de déplacer l'article."
+  itemMarkedDone: "Article marqué comme fait"
+  undo: Annuler
   createList: Nouvelle liste
   listName: Nom de la liste
   listDescription: Description (facultatif)

lib/messages_he.i18n.dart

@@ -708,6 +708,16 @@ class ChecklistsMessagesHe extends ChecklistsMessages {
   /// ```
   String get moveFailed => """העברת הפריט נכשלה.""";
 
+  /// ```dart
+  /// "הפריט סומן כהושלם"
+  /// ```
+  String get itemMarkedDone => """הפריט סומן כהושלם""";
+
+  /// ```dart
+  /// "בטל"
+  /// ```
+  String get undo => """בטל""";
+
   /// ```dart
   /// "רשימה חדשה"
   /// ```
@@ -1573,6 +1583,8 @@ Map<String, String> get messagesHeMap => {
   """checklists.removeItem""": """הסר פריט""",
   """checklists.moveItem""": """העבר לרשימה""",
   """checklists.moveFailed""": """העברת הפריט נכשלה.""",
+  """checklists.itemMarkedDone""": """הפריט סומן כהושלם""",
+  """checklists.undo""": """בטל""",
   """checklists.createList""": """רשימה חדשה""",
   """checklists.listName""": """שם הרשימה""",
   """checklists.listDescription""": """תיאור (אופציונלי)""",

lib/messages_he.i18n.yaml

@@ -129,6 +129,8 @@ checklists:
   removeItem: הסר פריט
   moveItem: העבר לרשימה
   moveFailed: העברת הפריט נכשלה.
+  itemMarkedDone: הפריט סומן כהושלם
+  undo: בטל
   createList: רשימה חדשה
   listName: שם הרשימה
   listDescription: תיאור (אופציונלי)

lib/views/checklists/checklists_view.dart

@@ -525,6 +525,34 @@ class _ReorderablePartition extends StatelessWidget {
     this.categorySpacing = 'disabled',
   });
 
+  void _toggleItem(
+    BuildContext context,
+    ChecklistsController controller,
+    ListItem item,
+  ) {
+    final wasDone = item.done;
+    controller.toggleItem(item);
+    if (wasDone) return;
+
+    final messenger = ScaffoldMessenger.of(context);
+    messenger.clearSnackBars();
+    messenger.showSnackBar(
+      SnackBar(
+        content: Text(m.checklists.itemMarkedDone),
+        action: SnackBarAction(
+          label: m.checklists.undo,
+          onPressed: () {
+            final current = controller.items.firstWhere(
+              (i) => i.id == item.id,
+              orElse: () => item.copyWith(done: true),
+            );
+            if (current.done) controller.toggleItem(current);
+          },
+        ),
+      ),
+    );
+  }
+
   void _viewItem(
     BuildContext context,
     ChecklistsController controller,
@@ -684,7 +712,7 @@ class _ReorderablePartition extends StatelessWidget {
               ? controller.categories[item.categoryId]
               : null,
           houseId: controller.houseId,
-          onToggle: controller.toggleItem,
+          onToggle: (item) => _toggleItem(context, controller, item),
           onView: (item) => _viewItem(context, controller, item),
           onEdit: (item) => _editItem(context, controller, item),
           onMove: (item) => _moveItem(context, controller, item),