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.

server/utils/cidaas.ts

@@ -256,6 +256,14 @@ export async function loginWithPassword(
       console.error('Cidaas password login failed:', errorData)
 
       // Handle specific errors
+      // Cidaas returns 400 with error: 'invalid_username_password' for invalid credentials
+      if (response.status === 400 && errorData.error === 'invalid_username_password') {
+        throw createError({
+          statusCode: 401,
+          statusMessage: 'Invalid email or password',
+        })
+      }
+
       if (response.status === 401) {
         throw createError({
           statusCode: 401,