Fix React error #130 - Remove authentication race condition

- Remove setTimeout delays in AdminAuthContext login function
- Make authentication state updates synchronous
- Replace setTimeout navigation with state-based navigation in AdminLoginPage
- Add proper error handling and component lifecycle management in CreateEventPage
- Prevent navigation if component unmounts during async operations

This fixes the issue where users would see React error #130 during login
and couldn't create events or save settings.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/src/pages/admin/AdminLoginPage.tsx

@@ -1,5 +1,5 @@
 import React, { useState } from 'react';
-import { useNavigate, Navigate } from 'react-router-dom';
+import { Navigate } from 'react-router-dom';
 import { Lock, Mail, Eye, EyeOff, AlertCircle } from 'lucide-react';
 import { toast } from 'react-toastify';
 
@@ -9,7 +9,6 @@ import { authService } from '../../services/auth.service';
 import { getAuthToken } from '../../config/api';
 
 export const AdminLoginPage: React.FC = () => {
-  const navigate = useNavigate();
   const { isAuthenticated, login } = useAdminAuth();
   
   const [formData, setFormData] = useState({
@@ -19,9 +18,10 @@ export const AdminLoginPage: React.FC = () => {
   const [showPassword, setShowPassword] = useState(false);
   const [isLoading, setIsLoading] = useState(false);
   const [errors, setErrors] = useState<Record<string, string>>({});
+  const [loginSuccess, setLoginSuccess] = useState(false);
 
-  // Redirect if already authenticated
-  if (isAuthenticated) {
+  // Redirect if already authenticated or login successful
+  if (isAuthenticated || loginSuccess) {
     return <Navigate to="/admin/dashboard" replace />;
   }
 
@@ -58,10 +58,7 @@ export const AdminLoginPage: React.FC = () => {
       const response = await authService.adminLogin(formData);
       login(response.token, response.user);
       toast.success('Login successful!');
-      // Add a small delay to ensure auth state is updated
-      setTimeout(() => {
-        navigate('/admin/dashboard');
-      }, 200);
+      setLoginSuccess(true);
     } catch (error: any) {
       console.error('Login error:', error);
       
@@ -71,9 +68,7 @@ export const AdminLoginPage: React.FC = () => {
         const token = getAuthToken(true);
         if (token) {
           // Login was successful, just had a connection issue
-          setTimeout(() => {
-            navigate('/admin/dashboard');
-          }, 200);
+          setLoginSuccess(true);
           return;
         }
         toast.error('Network error. Please check your connection and try again.');