refactor: update Ant Design imports to centralized path

- Replaced direct imports from 'antd' with centralized imports from '@/shared/antd-imports' to align with new import rules and improve maintainability.

worklenz-frontend/src/services/alerts/alertService.ts

@@ -1,6 +1,6 @@
 import { AlertType } from '@/types/alert.types';
 import DOMPurify from 'dompurify';
-import { notification } from 'antd';
+import { notification } from '@/shared/antd-imports';
 class AlertService {
   private static instance: AlertService;
   private activeAlerts: Set<string> = new Set();

worklenz-frontend/src/services/alerts/alertSlice.ts

@@ -1,6 +1,6 @@
 import { AlertConfig, AlertState, AlertType } from '@/types/alert.types';
 import { createSlice, PayloadAction } from '@reduxjs/toolkit';
-import { notification } from 'antd';
+import { notification } from '@/shared/antd-imports';
 import DOMPurify from 'dompurify';
 
 const initialState: AlertState = {