🎛️ refactor: HeaderBar into modular components, add shared skeletons, and primary-colored nav hover

Summary
- Split HeaderBar into maintainable components and hooks
- Centralized skeleton loading UI via a reusable SkeletonWrapper
- Improved navigation UX with primary-colored hover indication
- Preserved API surface and passed linters

Why
- Improve readability, reusability, and testability of the header
- Remove duplicated skeleton logic across files
- Provide clearer hover feedback consistent with the theme

What’s changed
- Components (web/src/components/layout/HeaderBar/)
  - New container: index.js
  - New UI components: HeaderLogo.js, Navigation.js, ActionButtons.js, UserArea.js, MobileMenuButton.js, NewYearButton.js, NotificationButton.js, ThemeToggle.js, LanguageSelector.js
  - New shared skeleton: SkeletonWrapper.js
  - Updated entry: HeaderBar.js now re-exports ./HeaderBar/index.js
- Hooks (web/src/hooks/common/)
  - New: useHeaderBar.js (state and actions for header)
  - New: useNotifications.js (announcements state, unread calc, open/close)
  - New: useNavigation.js (main nav link config)
- Skeleton refactor
  - Navigation.js: replaced inline skeletons with <SkeletonWrapper type="navigation" .../>
  - UserArea.js: replaced inline skeletons with <SkeletonWrapper type="userArea" .../>
  - HeaderLogo.js: replaced image/title skeletons with <SkeletonWrapper type="image"/>, <SkeletonWrapper type="title"/>
- Navigation hover UX
  - Added primary-colored hover to nav items for clearer pointer feedback
  - Final hover style: hover:text-semi-color-primary (kept rounded + transition classes)

Non-functional
- No breaking API changes; HeaderBar usage stays the same
- All modified files pass lint checks

Notes for future work
- SkeletonWrapper is extensible: add new cases (e.g., card) in one place
- Components are small and test-friendly; unit tests can be added per component

Affected files (key)
- web/src/components/layout/HeaderBar.js
- web/src/components/layout/HeaderBar/index.js
- web/src/components/layout/HeaderBar/Navigation.js
- web/src/components/layout/HeaderBar/UserArea.js
- web/src/components/layout/HeaderBar/HeaderLogo.js
- web/src/components/layout/HeaderBar/ActionButtons.js
- web/src/components/layout/HeaderBar/MobileMenuButton.js
- web/src/components/layout/HeaderBar/NewYearButton.js
- web/src/components/layout/HeaderBar/NotificationButton.js
- web/src/components/layout/HeaderBar/ThemeToggle.js
- web/src/components/layout/HeaderBar/LanguageSelector.js
- web/src/components/layout/HeaderBar/SkeletonWrapper.js
- web/src/hooks/common/useHeaderBar.js
- web/src/hooks/common/useNotifications.js
- web/src/hooks/common/useNavigation.js

web/src/components/layout/HeaderBar/NotificationButton.js

@@ -0,0 +1,45 @@
+/*
+Copyright (C) 2025 QuantumNous
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as
+published by the Free Software Foundation, either version 3 of the
+License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+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 { Button, Badge } from '@douyinfe/semi-ui';
+import { IconBell } from '@douyinfe/semi-icons';
+
+const NotificationButton = ({ unreadCount, onNoticeOpen, t }) => {
+  const buttonProps = {
+    icon: <IconBell className="text-lg" />,
+    'aria-label': t('系统公告'),
+    onClick: onNoticeOpen,
+    theme: "borderless",
+    type: "tertiary",
+    className: "!p-1.5 !text-current focus:!bg-semi-color-fill-1 dark:focus:!bg-gray-700 !rounded-full !bg-semi-color-fill-0 dark:!bg-semi-color-fill-1 hover:!bg-semi-color-fill-1 dark:hover:!bg-semi-color-fill-2",
+  };
+
+  if (unreadCount > 0) {
+    return (
+      <Badge count={unreadCount} type="danger" overflowCount={99}>
+        <Button {...buttonProps} size='small' />
+      </Badge>
+    );
+  }
+
+  return <Button {...buttonProps} />;
+};
+
+export default NotificationButton;