⚡️ perf: Defer Visactor chart libs to dashboard; minimize home bundle

Home started loading `/assets/visactor-*.js` due to static imports of `@visactor/react-vchart` and the Semi theme in dashboard components/hooks. This change moves chart dependencies to lazy/dynamic imports so they load only on dashboard routes.

Changes
- StatsCards.jsx: replace static `VChart` import with `React.lazy` + `Suspense` (fallback: null)
- ChartsPanel.jsx: replace static `VChart` import with `React.lazy` + `Suspense` (fallback: null)
- useDashboardCharts.js: remove static `initVChartSemiTheme` import; dynamically import and initialize the theme inside `useEffect` with a cancel guard

Behavior
- Home page no longer downloads `visactor` chunks on first load
- Chart libraries are fetched only when visiting `/console` (dashboard)
- No functional changes to chart rendering

Files
- web/src/components/dashboard/StatsCards.jsx
- web/src/components/dashboard/ChartsPanel.jsx
- web/src/hooks/dashboard/useDashboardCharts.js

Verification
- Build the app (`npm run build`) and open `/`: no `/assets/visactor-*.js` requests
- Navigate to `/console`: `visactor` chunks load and charts render as expected

Breaking Changes
- None

Follow-ups
- If needed, further trim homepage bundle by reducing heavy icon sets on the hero section

web/src/components/dashboard/StatsCards.jsx

@@ -17,9 +17,12 @@ along with this program. If not, see <https://www.gnu.org/licenses/>.
 For commercial licensing, please contact support@quantumnous.com
 */
 
-import React from 'react';
+import React, { Suspense } from 'react';
 import { Card, Avatar, Skeleton } from '@douyinfe/semi-ui';
-import { VChart } from '@visactor/react-vchart';
+
+const LazyVChart = React.lazy(() =>
+  import('@visactor/react-vchart').then(m => ({ default: m.VChart }))
+);
 
 const StatsCards = ({
   groupedStatsData,
@@ -74,10 +77,12 @@ const StatsCards = ({
                   </div>
                   {(loading || (item.trendData && item.trendData.length > 0)) && (
                     <div className="w-24 h-10">
-                      <VChart
-                        spec={getTrendSpec(item.trendData, item.trendColor)}
-                        option={CHART_CONFIG}
-                      />
+                      <Suspense fallback={null}>
+                        <LazyVChart
+                          spec={getTrendSpec(item.trendData, item.trendColor)}
+                          option={CHART_CONFIG}
+                        />
+                      </Suspense>
                     </div>
                   )}
                 </div>