Implement platform settings (Stage 9)

- Wire settings to actual platform behavior: maintenance mode, registration toggle,
  notification emails, curator feedback emails, email verification flag
- Add logo (logoUrl, showLogo) and social network links (YouTube, VK, Telegram) settings
- Show logo + school name dynamically in student layout header
- Add footer to student layout with org requisites and social links
- Register page: read settings server-side, validate terms checkbox with legal links
- Login page: show notice when redirected from closed registration
- Settings form: add Logo and Social Networks sections

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/(auth)/register/page.tsx

@@ -1,19 +1,32 @@
+import { redirect } from "next/navigation";
+import { getSettings } from "@/lib/settings";
 import { RegisterForm } from "./register-form";
 
-export default function RegisterPage() {
+export default async function RegisterPage() {
+  const settings = await getSettings();
+
+  if (settings.registrationEnabled !== "true") {
+    redirect("/login?notice=registration_closed");
+  }
+
   return (
     <div className="min-h-screen flex items-center justify-center" style={{ backgroundColor: "var(--background)" }}>
       <div className="w-full max-w-sm">
         <div className="text-center mb-8">
           <h1 className="text-2xl font-bold tracking-wide" style={{ color: "var(--foreground)" }}>
-            Second Brain
+            {settings.schoolName}
           </h1>
           <p className="mt-1 text-sm uppercase tracking-widest" style={{ color: "var(--muted-foreground)", fontSize: "0.65rem" }}>
             Образовательная платформа
           </p>
         </div>
         <div className="card-aubade p-8">
-          <RegisterForm />
+          <RegisterForm
+            showTermsCheckbox={settings.showTermsCheckbox === "true"}
+            privacyPolicyUrl={settings.privacyPolicyUrl}
+            termsUrl={settings.termsUrl}
+            offerUrl={settings.offerUrl}
+          />
         </div>
       </div>
     </div>