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)/login/page.tsx

@@ -1,17 +1,35 @@
+import { getSetting } from "@/lib/settings";
 import { LoginForm } from "./login-form";
 
-export default function LoginPage() {
+export default async function LoginPage({
+  searchParams,
+}: {
+  searchParams: Promise<{ notice?: string }>;
+}) {
+  const [schoolName, { notice }] = await Promise.all([
+    getSetting("schoolName"),
+    searchParams,
+  ]);
+
   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
+            {schoolName}
           </h1>
           <p className="mt-1 text-sm uppercase tracking-widest" style={{ color: "var(--muted-foreground)", fontSize: "0.65rem" }}>
             Образовательная платформа
           </p>
         </div>
+        {notice === "registration_closed" && (
+          <div
+            className="mb-4 px-4 py-3 text-sm text-center"
+            style={{ border: "2px solid var(--border)", color: "var(--muted-foreground)" }}
+          >
+            Регистрация временно закрыта. Обратитесь к администратору.
+          </div>
+        )}
         <div className="card-aubade p-8">
           <LoginForm />
         </div>

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>

src/app/(auth)/register/register-form.tsx

@@ -4,10 +4,18 @@ import { useState } from "react";
 import Link from "next/link";
 import { signUp } from "@/lib/auth-client";
 
-export function RegisterForm() {
+interface Props {
+  showTermsCheckbox: boolean;
+  privacyPolicyUrl: string;
+  termsUrl: string;
+  offerUrl: string;
+}
+
+export function RegisterForm({ showTermsCheckbox, privacyPolicyUrl, termsUrl, offerUrl }: Props) {
   const [name, setName] = useState("");
   const [email, setEmail] = useState("");
   const [password, setPassword] = useState("");
+  const [termsAccepted, setTermsAccepted] = useState(false);
   const [error, setError] = useState("");
   const [loading, setLoading] = useState(false);
   const [success, setSuccess] = useState(false);
@@ -22,8 +30,18 @@ export function RegisterForm() {
     fontFamily: "inherit",
   } as React.CSSProperties;
 
+  const legalLinks = [
+    { url: privacyPolicyUrl, label: "Политику конфиденциальности" },
+    { url: termsUrl, label: "Согласие на обработку данных" },
+    { url: offerUrl, label: "Договор-оферту" },
+  ].filter((l) => l.url);
+
   async function handleSubmit(e: React.FormEvent) {
     e.preventDefault();
+    if (showTermsCheckbox && !termsAccepted) {
+      setError("Необходимо принять условия для продолжения");
+      return;
+    }
     setError("");
     setLoading(true);
 
@@ -102,6 +120,38 @@ export function RegisterForm() {
           placeholder="Минимум 8 символов"
         />
       </div>
+
+      {showTermsCheckbox && (
+        <label className="flex items-start gap-2 cursor-pointer">
+          <input
+            type="checkbox"
+            checked={termsAccepted}
+            onChange={(e) => setTermsAccepted(e.target.checked)}
+            className="mt-0.5 flex-shrink-0"
+            style={{ width: "16px", height: "16px", accentColor: "var(--foreground)" }}
+          />
+          <span className="text-xs" style={{ color: "var(--muted-foreground)" }}>
+            Я принимаю{" "}
+            {legalLinks.length > 0
+              ? legalLinks.map((l, i) => (
+                  <span key={l.url}>
+                    <a
+                      href={l.url}
+                      target="_blank"
+                      rel="noopener noreferrer"
+                      className="underline"
+                      style={{ color: "var(--foreground)" }}
+                    >
+                      {l.label}
+                    </a>
+                    {i < legalLinks.length - 1 ? ", " : ""}
+                  </span>
+                ))
+              : "условия использования платформы"}
+          </span>
+        </label>
+      )}
+
       {error && (
         <p className="text-xs py-2 px-3" style={{ border: "2px solid oklch(0.577 0.245 27.325)", color: "oklch(0.577 0.245 27.325)" }}>
           {error}