feat(admin): add registration policy settings and disabled register state

apps/admin/src/app/login/login-form.tsx

@@ -8,7 +8,7 @@ import { AdminLocaleSwitcher } from "@/components/admin-locale-switcher"
 import { useAdminT } from "@/providers/admin-i18n-provider"
 
 type LoginFormProps = {
-  mode: "signin" | "signup-owner" | "signup-user"
+  mode: "signin" | "signup-owner" | "signup-user" | "signup-disabled"
 }
 
 type AuthResponse = {
@@ -41,6 +41,7 @@ export function LoginForm({ mode }: LoginFormProps) {
   const [isBusy, setIsBusy] = useState(false)
   const [error, setError] = useState<string | null>(null)
   const [success, setSuccess] = useState<string | null>(null)
+  const canSubmitSignUp = mode === "signup-owner" || mode === "signup-user"
 
   async function handleSignIn(event: FormEvent<HTMLFormElement>) {
     event.preventDefault()
@@ -141,7 +142,9 @@ export function LoginForm({ mode }: LoginFormProps) {
             ? t("auth.titles.signIn", "Sign in to CMS Admin")
             : mode === "signup-owner"
               ? t("auth.titles.signUpOwner", "Welcome to CMS Admin")
-              : t("auth.titles.signUpUser", "Create an admin account")}
+              : mode === "signup-user"
+                ? t("auth.titles.signUpUser", "Create an admin account")
+                : t("auth.titles.signUpDisabled", "Registration is disabled")}
         </h1>
         <p className="text-sm text-neutral-600">
           {mode === "signin"
@@ -151,7 +154,12 @@ export function LoginForm({ mode }: LoginFormProps) {
                   "auth.descriptions.signUpOwner",
                   "Create the first owner account to initialize this admin instance.",
                 )
-              : t("auth.descriptions.signUpUser", "Self-registration is enabled for admin users.")}
+              : mode === "signup-user"
+                ? t("auth.descriptions.signUpUser", "Self-registration is enabled for admin users.")
+                : t(
+                    "auth.descriptions.signUpDisabled",
+                    "Self-registration is currently turned off by an administrator.",
+                  )}
         </p>
       </div>
 
@@ -208,7 +216,7 @@ export function LoginForm({ mode }: LoginFormProps) {
 
           {error ? <p className="text-sm text-red-600">{error}</p> : null}
         </form>
-      ) : (
+      ) : canSubmitSignUp ? (
         <form
           onSubmit={handleSignUp}
           className="mt-8 space-y-4 rounded-xl border border-neutral-200 p-6"
@@ -290,6 +298,20 @@ export function LoginForm({ mode }: LoginFormProps) {
           {error ? <p className="text-sm text-red-600">{error}</p> : null}
           {success ? <p className="text-sm text-green-700">{success}</p> : null}
         </form>
+      ) : (
+        <section className="mt-8 space-y-4 rounded-xl border border-neutral-200 p-6">
+          <p className="text-sm text-neutral-700">
+            {t(
+              "auth.messages.registrationDisabled",
+              "Registration is disabled for this admin instance. Ask an administrator to create an account or enable self-registration.",
+            )}
+          </p>
+          <p className="text-xs text-neutral-600">
+            <Link href={`/login?next=${encodeURIComponent(nextPath)}`} className="underline">
+              {t("auth.links.goToSignIn", "Go to sign in")}
+            </Link>
+          </p>
+        </section>
       )}
     </main>
   )