feat(navbar): implement new notification and invitation components

- Added NotificationDrawer and InvitationItem components to enhance the notification system.
- Refactored existing notification handling to improve user experience and maintainability.
- Introduced new styles and structure for notifications using Tailwind CSS for better visual consistency.
- Updated Navbar to include new components and improve overall layout.
- Created a centralized navRoutes file for better route management within the navbar.

worklenz-frontend/src/components/navbar/upgradePlan/UpgradePlanButton.tsx

@@ -0,0 +1,35 @@
+import { Button, Tooltip } from '@/shared/antd-imports';
+import React, { memo, useCallback } from 'react';
+import { colors } from '../../../styles/colors';
+import { useTranslation } from 'react-i18next';
+import { useNavigate } from 'react-router-dom';
+import { useAppSelector } from '@/hooks/useAppSelector';
+
+const UpgradePlanButton = memo(() => {
+  // localization
+  const { t } = useTranslation('navbar');
+  const navigate = useNavigate();
+
+  const themeMode = useAppSelector(state => state.themeReducer.mode);
+
+  return (
+    <Tooltip title={t('upgradePlanTooltip')}>
+      <Button
+        style={{
+          backgroundColor: themeMode === 'dark' ? '#b38750' : colors.lightBeige,
+          color: '#000000d9',
+          padding: '4px 11px',
+        }}
+        size="small"
+        type="text"
+        onClick={useCallback(() => navigate('/worklenz/admin-center/billing'), [navigate])}
+      >
+        {t('upgradePlan')}
+      </Button>
+    </Tooltip>
+  );
+});
+
+UpgradePlanButton.displayName = 'UpgradePlanButton';
+
+export default UpgradePlanButton;