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/lib/stores/dashboard-store.ts

@@ -81,8 +81,8 @@ export const useDashboardStore = create<DashboardState>()((set, get) => ({
           isDirty: true,
         };
       });
-    } catch {
-      set({ error: 'Failed to add widget' });
+    } catch (err) {
+      console.error('Failed to add widget:', err);
     }
   },
 
@@ -100,8 +100,8 @@ export const useDashboardStore = create<DashboardState>()((set, get) => ({
           isDirty: true,
         };
       });
-    } catch {
-      set({ error: 'Failed to remove widget' });
+    } catch (err) {
+      console.error('Failed to remove widget:', err);
     }
   },
 
@@ -129,8 +129,8 @@ export const useDashboardStore = create<DashboardState>()((set, get) => ({
     try {
       await api.saveLayout(get().layouts);
       set({ isDirty: false });
-    } catch {
-      set({ error: 'Failed to save layout' });
+    } catch (err) {
+      console.error('Failed to save layout:', err);
     }
   },
 }));