fix(auth): accept configured public origin for sign-in

frontend/app/login/page.tsx

@@ -1,7 +1,8 @@
 "use client";
 
-import { useEffect, useState, type FormEvent } from "react";
+import { type FormEvent, useEffect, useState } from "react";
 import { getApiBase, setToken } from "../lib/auth";
+import { loginErrorMessage } from "../lib/login-errors";
 import AuthLayout from "../ui/AuthLayout";
 
 type LoginMode = "jellyfin" | "local";
@@ -73,15 +74,7 @@ export default function LoginPage() {
         },
       );
       if (!response.ok) {
-        setError(
-          response.status === 429
-            ? "Too many attempts. Please wait a moment and try again."
-            : response.status >= 500
-              ? "Sign-in is temporarily unavailable. Please try again shortly."
-              : response.status === 403
-                ? "This account cannot sign in. Please contact an administrator."
-                : "Check your username and password, then try again.",
-        );
+        setError(await loginErrorMessage(response));
         return;
       }
       const data = await response.json();