🎨 refactor(ui): use lucide-react for search/refresh and chevron icons

- DashboardHeader.jsx: replace Semi's IconSearch/IconRefresh with lucide-react's Search/RefreshCw (size 16), preserve existing button styles
- UptimePanel.jsx: replace Semi's IconRefresh with lucide-react's RefreshCw (size 14), keep styling intact
- UserArea.jsx: replace Semi's IconChevronDown with lucide-react's ChevronDown (size 14), preserve visual parity
- Update imports: remove @douyinfe/semi-icons usage where replaced; add lucide-react imports
- Verified no remaining IconSearch/IconRefresh in dashboard; no new linter errors

Motivation: unify icon library for core actions and improve UI consistency.
Follow-ups: consider migrating remaining Semi icons (e.g., plus/minus, charts) to lucide-react.

web/src/components/layout/HeaderBar/UserArea.jsx

@@ -25,8 +25,8 @@ import {
   Dropdown,
   Typography,
 } from '@douyinfe/semi-ui';
+import { ChevronDown } from 'lucide-react';
 import {
-  IconChevronDown,
   IconExit,
   IconUserSetting,
   IconCreditCard,
@@ -120,7 +120,7 @@ const UserArea = ({
               {userState.user.username}
             </Typography.Text>
           </span>
-          <IconChevronDown className="text-xs text-semi-color-text-2 dark:text-gray-400" />
+          <ChevronDown size={14} className="text-xs text-semi-color-text-2 dark:text-gray-400" />
         </Button>
       </Dropdown>
     );