Replace composable with Pinia store for persistent auth state

pages/login.vue

@@ -101,7 +101,7 @@ import { useRouter } from 'vue-router'
 import { AlertCircle, Check, Loader2, Lock } from 'lucide-vue-next'
 
 const router = useRouter()
-const { checkAuth } = useAuth()
+const authStore = useAuthStore()
 
 const formData = ref({
   email: '',
@@ -118,20 +118,11 @@ const handleLogin = async () => {
   successMessage.value = ''
 
   try {
-    const response = await $fetch('/api/auth/login', {
-      method: 'POST',
-      body: {
-        email: formData.value.email,
-        password: formData.value.password
-      }
-    })
+    const response = await authStore.login(formData.value.email, formData.value.password)
 
     if (response.success) {
       successMessage.value = 'Anmeldung erfolgreich! Sie werden weitergeleitet...'
       
-      // Update global auth state
-      await checkAuth()
-      
       // Redirect based on role
       setTimeout(() => {
         if (response.user.role === 'admin' || response.user.role === 'vorstand') {