feat(quick-260916-bwo): Dashboard-Raster verdoppelt (24 Spalten, 20 px, 8 px Abstand), Konstanten x2, einmalige Umrechnung gespeicherter Anordnungen mit Marker __gridVersion

- dashboard-grid.tsx: COLS 24/20/12/8/2, rowHeight 20, margin 8 (containerPadding folgt), Rueckfallwerte 4
- widget-registry.tsx: alle 32 Werte in WIDGET_CONSTRAINTS verdoppelt
- grid-layout-migration.ts (neu): migrateGridLayouts/withGridVersion, Marker nur im JSON, Idempotenz (T-BWO-02)
- dashboard-store.ts: Umrechnung beim Laden, Sofort-Speichern mit Marker, withGridVersion bei jedem saveLayout
- Tests: Migration 7 (neu), Store 6 (neu), Registry +1 (Tabelle), Grid +2 (Props ueber Mock), API-Spec +2 (Durchreichung __gridVersion, timeFontSizePt)

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018N9CD3ebPKm1b32bPpBknY

apps/web/src/components/dashboard/dashboard-grid.test.tsx

@@ -1,3 +1,4 @@
+import { Children, isValidElement } from 'react';
 import { cleanup, render, screen } from '@testing-library/react';
 import { afterEach, describe, expect, it, vi } from 'vitest';
 
@@ -34,13 +35,15 @@ vi.mock('next-intl', () => ({
   },
 }));
 
-// Mock react-grid-layout Responsive to a simple passthrough for jsdom stability
+// Mock react-grid-layout Responsive to a simple passthrough for jsdom stability.
+// quick-260916-bwo: der Mock faengt zusaetzlich die Props ein, damit die
+// Raster-Konstanten (cols, rowHeight, margin, breakpoints) pruefbar sind.
+const captured = vi.hoisted(() => ({ props: null as Record<string, unknown> | null }));
 vi.mock('react-grid-layout', () => ({
-  Responsive: ({
-    children,
-  }: {
-    children: React.ReactNode;
-  }) => <div data-testid="responsive-grid">{children}</div>,
+  Responsive: (props: Record<string, unknown> & { children: React.ReactNode }) => {
+    captured.props = props;
+    return <div data-testid="responsive-grid">{props.children}</div>;
+  },
   noCompactor: () => null,
 }));
 
@@ -153,4 +156,46 @@ describe('DashboardGrid', () => {
     expect(screen.getByLabelText('Remove widget')).toBeInTheDocument();
     expect(document.querySelector('.widget-drag-handle')).toBeInTheDocument();
   });
+
+  it('quick-260916-bwo Test 4: Grid-Props — 24/20/12/8/2 Spalten, rowHeight 20, margin 8, Breakpoints unveraendert, containerPadding folgt dem margin', async () => {
+    captured.props = null;
+    const { DashboardGrid } = await import('./dashboard-grid');
+    render(
+      <DashboardGrid
+        layouts={{ lg: [{ i: 'inst-1', x: 0, y: 0, w: 4, h: 4 }], md: [], sm: [], xs: [], xxs: [] }}
+        widgets={[{ id: 'inst-1', widgetType: 'clock', config: {} }]}
+        isEditMode={false}
+        onLayoutChange={vi.fn()}
+        onRemoveWidget={vi.fn()}
+      />,
+    );
+
+    expect(captured.props).not.toBeNull();
+    expect(captured.props?.cols).toEqual({ lg: 24, md: 20, sm: 12, xs: 8, xxs: 2 });
+    expect(captured.props?.rowHeight).toBe(20);
+    expect(captured.props?.margin).toEqual([8, 8]);
+    expect(captured.props?.breakpoints).toEqual({ lg: 1200, md: 996, sm: 768, xs: 480, xxs: 0 });
+    expect(captured.props?.containerPadding).toBeUndefined();
+  });
+
+  it('quick-260916-bwo Test 5: Widget ohne gespeicherten Eintrag bekommt die verdoppelten Vorgaben als data-grid', async () => {
+    captured.props = null;
+    const { DashboardGrid } = await import('./dashboard-grid');
+    render(
+      <DashboardGrid
+        layouts={{ lg: [], md: [], sm: [], xs: [], xxs: [] }}
+        widgets={[{ id: 'inst-3', widgetType: 'clock', config: {} }]}
+        isEditMode={false}
+        onLayoutChange={vi.fn()}
+        onRemoveWidget={vi.fn()}
+      />,
+    );
+
+    const children = Children.toArray(captured.props?.children as React.ReactNode);
+    expect(children).toHaveLength(1);
+    const first = children[0];
+    expect(isValidElement(first)).toBe(true);
+    const props = (first as React.ReactElement<Record<string, unknown>>).props;
+    expect(props['data-grid']).toEqual({ x: 0, y: 0, w: 4, h: 4, minW: 4, minH: 4 });
+  });
 });