feat: admin panel with SQLite, auth, and calendar-style schedule editor

Complete admin panel for content management:
- SQLite database with better-sqlite3, seed script from content.ts
- Simple password auth with HMAC-signed cookies (Edge + Node compatible)
- 9 section editors: meta, hero, about, team, classes, schedule, pricing, FAQ, contact
- Team CRUD with image upload and drag reorder
- Schedule editor with Google Calendar-style visual timeline (colored blocks, overlap detection, click-to-add)
- All public components refactored to accept data props from DB (with fallback to static content)
- Middleware protecting /admin/* and /api/admin/* routes

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

src/app/admin/layout.tsx

@@ -0,0 +1,146 @@
+"use client";
+
+import { useState } from "react";
+import Link from "next/link";
+import { usePathname, useRouter } from "next/navigation";
+import {
+  LayoutDashboard,
+  Sparkles,
+  Users,
+  BookOpen,
+  Calendar,
+  DollarSign,
+  HelpCircle,
+  Phone,
+  FileText,
+  Globe,
+  LogOut,
+  Menu,
+  X,
+  ChevronLeft,
+} from "lucide-react";
+
+const NAV_ITEMS = [
+  { href: "/admin", label: "Дашборд", icon: LayoutDashboard },
+  { href: "/admin/meta", label: "SEO / Мета", icon: Globe },
+  { href: "/admin/hero", label: "Главный экран", icon: Sparkles },
+  { href: "/admin/about", label: "О студии", icon: FileText },
+  { href: "/admin/team", label: "Команда", icon: Users },
+  { href: "/admin/classes", label: "Направления", icon: BookOpen },
+  { href: "/admin/schedule", label: "Расписание", icon: Calendar },
+  { href: "/admin/pricing", label: "Цены", icon: DollarSign },
+  { href: "/admin/faq", label: "FAQ", icon: HelpCircle },
+  { href: "/admin/contact", label: "Контакты", icon: Phone },
+];
+
+export default function AdminLayout({
+  children,
+}: {
+  children: React.ReactNode;
+}) {
+  const pathname = usePathname();
+  const router = useRouter();
+  const [sidebarOpen, setSidebarOpen] = useState(false);
+
+  // Don't render admin shell on login page
+  if (pathname === "/admin/login") {
+    return <>{children}</>;
+  }
+
+  async function handleLogout() {
+    await fetch("/api/logout", { method: "POST" });
+    router.push("/admin/login");
+  }
+
+  function isActive(href: string) {
+    if (href === "/admin") return pathname === "/admin";
+    return pathname.startsWith(href);
+  }
+
+  return (
+    <div className="flex min-h-screen bg-neutral-950 text-white">
+      {/* Mobile overlay */}
+      {sidebarOpen && (
+        <div
+          className="fixed inset-0 z-40 bg-black/60 lg:hidden"
+          onClick={() => setSidebarOpen(false)}
+        />
+      )}
+
+      {/* Sidebar */}
+      <aside
+        className={`fixed inset-y-0 left-0 z-50 flex w-64 flex-col border-r border-white/10 bg-neutral-900 transition-transform lg:static lg:translate-x-0 ${
+          sidebarOpen ? "translate-x-0" : "-translate-x-full"
+        }`}
+      >
+        <div className="flex items-center justify-between border-b border-white/10 px-5 py-4">
+          <Link href="/admin" className="text-lg font-bold">
+            BLACK HEART
+          </Link>
+          <button
+            onClick={() => setSidebarOpen(false)}
+            className="lg:hidden text-neutral-400 hover:text-white"
+          >
+            <X size={20} />
+          </button>
+        </div>
+
+        <nav className="flex-1 overflow-y-auto p-3 space-y-1">
+          {NAV_ITEMS.map((item) => {
+            const Icon = item.icon;
+            const active = isActive(item.href);
+            return (
+              <Link
+                key={item.href}
+                href={item.href}
+                onClick={() => setSidebarOpen(false)}
+                className={`flex items-center gap-3 rounded-lg px-3 py-2.5 text-sm transition-colors ${
+                  active
+                    ? "bg-gold/10 text-gold font-medium"
+                    : "text-neutral-400 hover:text-white hover:bg-white/5"
+                }`}
+              >
+                <Icon size={18} />
+                {item.label}
+              </Link>
+            );
+          })}
+        </nav>
+
+        <div className="border-t border-white/10 p-3 space-y-1">
+          <Link
+            href="/"
+            target="_blank"
+            className="flex items-center gap-3 rounded-lg px-3 py-2.5 text-sm text-neutral-400 hover:text-white hover:bg-white/5 transition-colors"
+          >
+            <ChevronLeft size={18} />
+            Открыть сайт
+          </Link>
+          <button
+            onClick={handleLogout}
+            className="flex w-full items-center gap-3 rounded-lg px-3 py-2.5 text-sm text-neutral-400 hover:text-red-400 hover:bg-white/5 transition-colors"
+          >
+            <LogOut size={18} />
+            Выйти
+          </button>
+        </div>
+      </aside>
+
+      {/* Main content */}
+      <div className="flex-1 flex flex-col min-w-0">
+        {/* Top bar (mobile) */}
+        <header className="flex items-center gap-3 border-b border-white/10 px-4 py-3 lg:hidden">
+          <button
+            onClick={() => setSidebarOpen(true)}
+            className="text-neutral-400 hover:text-white"
+          >
+            <Menu size={24} />
+          </button>
+          <span className="font-bold">BLACK HEART</span>
+        </header>
+
+        <main className="flex-1 p-4 sm:p-6 lg:p-8">{children}</main>
+      </div>
+    </div>
+  );
+}