Fix tutorial leaving tiles extremely small after completion

GridStack v12 removeInternalForSave() deletes w/h properties from
save() output when they equal minW/minH (or 1). This caused
_removeDemoView() to pass h:undefined to grid.update(), which
GridStack then defaulted to h:1, shrinking all tiles.

Fix: save layout by reading node properties directly instead of
using _grid.save(false), ensuring w and h are always preserved.

src/static/js/tutorial.js

@@ -194,7 +194,7 @@ const Tutorial = {
         }
         // Aktuelles Layout sichern und Standard-Layout erzwingen
         if (typeof LayoutManager !== 'undefined' && LayoutManager._grid) {
-            this._savedState.savedLayout = LayoutManager._grid.save(false);
+            this._savedState.savedLayout = LayoutManager._grid.engine.nodes.map(function(n) { return { id: n.el ? n.el.getAttribute("gs-id") : n.id, x: n.x, y: n.y, w: n.w, h: n.h }; });
             LayoutManager._applyLayout(LayoutManager.DEFAULT_LAYOUT);
         }
         // GridStack Resize triggern damit Kacheln korrekt positioniert werden