♻️ refactor(web): migrate React modules from .js to .jsx and align entrypoint

- Rename React components/pages/utilities that contain JSX to `.jsx` across `web/src`
- Update import paths and re-exports to match new `.jsx` extensions
- Fix Vite entry by switching `web/index.html` from `/src/index.js` to `/src/index.jsx`
- Verified remaining `.js` files are plain JS (hooks/helpers/constants) and do not require JSX
- No runtime behavior changes; extension and reference alignment only

Context: Resolves the Vite pre-transform error caused by the stale `/src/index.js` entry after migrating to `.jsx`.

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

@@ -0,0 +1,78 @@
+/*
+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 NewYearButton from './NewYearButton';
+import NotificationButton from './NotificationButton';
+import ThemeToggle from './ThemeToggle';
+import LanguageSelector from './LanguageSelector';
+import UserArea from './UserArea';
+
+const ActionButtons = ({
+  isNewYear,
+  unreadCount,
+  onNoticeOpen,
+  theme,
+  onThemeToggle,
+  currentLang,
+  onLanguageChange,
+  userState,
+  isLoading,
+  isMobile,
+  isSelfUseMode,
+  logout,
+  navigate,
+  t,
+}) => {
+  return (
+    <div className="flex items-center gap-2 md:gap-3">
+      <NewYearButton isNewYear={isNewYear} />
+
+      <NotificationButton
+        unreadCount={unreadCount}
+        onNoticeOpen={onNoticeOpen}
+        t={t}
+      />
+
+      <ThemeToggle
+        theme={theme}
+        onThemeToggle={onThemeToggle}
+        t={t}
+      />
+
+      <LanguageSelector
+        currentLang={currentLang}
+        onLanguageChange={onLanguageChange}
+        t={t}
+      />
+
+      <UserArea
+        userState={userState}
+        isLoading={isLoading}
+        isMobile={isMobile}
+        isSelfUseMode={isSelfUseMode}
+        logout={logout}
+        navigate={navigate}
+        t={t}
+      />
+    </div>
+  );
+};
+
+export default ActionButtons;