Refactor login error handling and improve user feedback

- Update LoginForm component to display error messages directly from the authentication response.
- Modify useAuth composable to handle login errors more effectively, ensuring proper error messages are thrown.
- Enhance login API response to return structured error messages for invalid credentials.
- Adjust Cidaas utility to throw specific errors for invalid username/password scenarios.

app/components/Auth/LoginForm.vue

@@ -32,19 +32,14 @@ const onSubmit = handleSubmit(async (values) => {
     // Redirect happens in login() function
   } catch (error: any) {
     console.error('Login error:', error)
-    submitError.value = error.data?.message || 'Anmeldung fehlgeschlagen. Bitte versuchen Sie es erneut.'
+    // Error message is now directly in error.message (thrown by useAuth composable)
+    submitError.value = error.message || 'Anmeldung fehlgeschlagen. Bitte versuchen Sie es erneut.'
   }
 })
 </script>
 
 <template>
   <form @submit="onSubmit" class="space-y-6">
-    <!-- Error Alert -->
-    <Alert v-if="submitError" class="border-destructive bg-destructive/10 text-white">
-      <AlertCircle class="h-5 w-5 text-destructive" />
-      <AlertDescription class="text-white/90">{{ submitError }}</AlertDescription>
-    </Alert>
-
     <!-- Email Field -->
     <FormField v-slot="{ componentField }" name="email">
       <FormItem>
@@ -67,6 +62,12 @@ const onSubmit = handleSubmit(async (values) => {
       </FormItem>
     </FormField>
 
+    <!-- Error Alert -->
+    <Alert v-if="submitError" class="border-destructive bg-destructive/10 text-white">
+      <AlertCircle class="h-5 w-5 text-destructive" />
+      <AlertDescription class="text-white/90">{{ submitError }}</AlertDescription>
+    </Alert>
+
     <!-- Submit Button -->
     <Button type="submit" variant="experimenta" size="experimenta" class="w-full" :disabled="isSubmitting">
       <Loader2 v-if="isSubmitting" class="mr-2 h-5 w-5 animate-spin" />