fix(dashboard): noCompactor + note edit/preview toggle + widget border

- dashboard-grid: add noCompactor to prevent auto-compaction on drag
- note-widget: edit/preview toggle button (pencil icon), isEditing state,
  hideToolbar in preview mode
- widget-wrapper: border-primary/20 accent border
- dashboard-store: console.error on widget add/remove/layout-save failures

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

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

@@ -1,7 +1,7 @@
 'use client';
 
 import { useEffect, useRef, useState } from 'react';
-import { Responsive } from 'react-grid-layout';
+import { Responsive, noCompactor } from 'react-grid-layout';
 import type { ResponsiveLayouts } from 'react-grid-layout';
 import 'react-grid-layout/css/styles.css';
 import 'react-resizable/css/styles.css';
@@ -97,6 +97,7 @@ export function DashboardGrid({
         resizeConfig={{
           enabled: isEditMode,
         }}
+        compactor={noCompactor}
         onLayoutChange={(_currentLayout, allLayouts) => onLayoutChange(allLayouts)}
       >
         {widgets.map((widget) => {