Show helpful error message for Discord email mismatch

cgen-c16fcef1fb7b4861aafe135456edb293

client/pages/Login.tsx

@@ -96,6 +96,11 @@ export default function Login() {
           title: "Authentication Error",
           description: errorMessage,
         });
+      } else if (errorType === "discord_no_match") {
+        toastError({
+          title: "Discord Email Not Found",
+          description: decodeURIComponent(errorMessage) || "Your Discord email doesn't match any existing AeThex account. Please sign in with your email first.",
+        });
       }
     }
   }, [location.search, toastError]);