feat: admin panel — SMTP, topic bank, maintenance mode UI

AdminTopicBank.js: банк тем блога по категориям
  Аккордеон: неиспользованные + использованные темы
  Прогресс-бар использования, кнопка +10 AI (фоновая генерация)
  Мультистрочное добавление (одна строка = одна тема)
AdminPanel: + Email/SMTP + Банк тем блога + Mail иконка
SmtpTestButton: тест отправки прямо в разделе SMTP
API routes: /api/admin/blog-topics, /[id], /generate, /api/admin/email/test

app/api/admin/blog-topics/[id]/route.js

@@ -0,0 +1,13 @@
+import { NextResponse } from 'next/server';
+import { requireUser } from '@/lib/session';
+
+const ENGINE_URL    = process.env.ENGINE_URL    || 'http://127.0.0.1:3030';
+const ENGINE_SECRET = process.env.ENGINE_SECRET || '';
+const h = (uid) => ({ 'x-internal-secret': ENGINE_SECRET, 'x-user-id': String(uid) });
+
+export async function DELETE(req, { params }) {
+  const user = await requireUser();
+  if (!user?.isAdmin) return NextResponse.json({ error: 'Forbidden' }, { status: 403 });
+  const res = await fetch(`${ENGINE_URL}/api/admin/blog-topics/${params.id}`, { method: 'DELETE', headers: h(user.id) });
+  return NextResponse.json(await res.json());
+}

app/api/admin/blog-topics/generate/route.js

@@ -0,0 +1,16 @@
+import { NextResponse } from 'next/server';
+import { requireUser } from '@/lib/session';
+
+const ENGINE_URL    = process.env.ENGINE_URL    || 'http://127.0.0.1:3030';
+const ENGINE_SECRET = process.env.ENGINE_SECRET || '';
+const h = (uid) => ({ 'x-internal-secret': ENGINE_SECRET, 'x-user-id': String(uid) });
+
+export async function POST(req) {
+  const user = await requireUser();
+  if (!user?.isAdmin) return NextResponse.json({ error: 'Forbidden' }, { status: 403 });
+  const body = await req.json();
+  const res = await fetch(`${ENGINE_URL}/api/admin/blog-topics/generate`, {
+    method: 'POST', headers: { ...h(user.id), 'Content-Type': 'application/json' }, body: JSON.stringify(body),
+  });
+  return NextResponse.json(await res.json());
+}

app/api/admin/blog-topics/route.js

@@ -0,0 +1,26 @@
+import { NextResponse } from 'next/server';
+import { requireUser } from '@/lib/session';
+
+const ENGINE_URL    = process.env.ENGINE_URL    || 'http://127.0.0.1:3030';
+const ENGINE_SECRET = process.env.ENGINE_SECRET || '';
+const h = (uid) => ({ 'x-internal-secret': ENGINE_SECRET, 'x-user-id': String(uid) });
+
+// GET — список тем
+export async function GET(req) {
+  const user = await requireUser();
+  if (!user?.isAdmin) return NextResponse.json({ error: 'Forbidden' }, { status: 403 });
+  const { searchParams } = new URL(req.url);
+  const res = await fetch(`${ENGINE_URL}/api/admin/blog-topics?${searchParams}`, { headers: h(user.id), cache: 'no-store' });
+  return NextResponse.json(await res.json());
+}
+
+// POST — добавить тему
+export async function POST(req) {
+  const user = await requireUser();
+  if (!user?.isAdmin) return NextResponse.json({ error: 'Forbidden' }, { status: 403 });
+  const body = await req.json();
+  const res = await fetch(`${ENGINE_URL}/api/admin/blog-topics`, {
+    method: 'POST', headers: { ...h(user.id), 'Content-Type': 'application/json' }, body: JSON.stringify(body),
+  });
+  return NextResponse.json(await res.json(), { status: res.status });
+}

app/api/admin/email/test/route.js

@@ -0,0 +1,16 @@
+import { NextResponse } from 'next/server';
+import { requireUser } from '@/lib/session';
+
+const ENGINE_URL    = process.env.ENGINE_URL    || 'http://127.0.0.1:3030';
+const ENGINE_SECRET = process.env.ENGINE_SECRET || '';
+const h = (uid) => ({ 'x-internal-secret': ENGINE_SECRET, 'x-user-id': String(uid) });
+
+export async function POST(req) {
+  const user = await requireUser();
+  if (!user?.isAdmin) return NextResponse.json({ error: 'Forbidden' }, { status: 403 });
+  const body = await req.json();
+  const res = await fetch(`${ENGINE_URL}/api/admin/email/test`, {
+    method: 'POST', headers: { ...h(user.id), 'Content-Type': 'application/json' }, body: JSON.stringify(body),
+  });
+  return NextResponse.json(await res.json(), { status: res.status });
+}