fix: Refactor imports in OfflineMode, Settings, and API services

### Summary of Changes
- Removed unused imports from `OfflineMode.js` and `Settings.js` to streamline the code.
- Cleaned up the import statements in `api.js` by eliminating the unused `formatServiceData` and `formatEventData` functions.

### Expected Results
- Improved code clarity and maintainability by adhering to clean code principles and reducing unnecessary dependencies.

frontend/src/components/OfflineMode.js

@@ -1,6 +1,6 @@
 import React from 'react';
 import { Alert, Button, Space } from 'antd';
-import { WifiOutlined, ReloadOutlined } from '@ant-design/icons';
+import { ReloadOutlined } from '@ant-design/icons';
 
 const OfflineMode = ({ onRetry }) => {
   return (