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/middleware.ts

@@ -0,0 +1,28 @@
+import { NextRequest, NextResponse } from "next/server";
+import { verifyToken, COOKIE_NAME } from "@/lib/auth-edge";
+
+export async function middleware(request: NextRequest) {
+  const { pathname } = request.nextUrl;
+
+  // Allow login page and login API
+  if (pathname === "/admin/login" || pathname === "/api/auth/login") {
+    return NextResponse.next();
+  }
+
+  // Protect /admin/* and /api/admin/*
+  const token = request.cookies.get(COOKIE_NAME)?.value;
+  const valid = token ? await verifyToken(token) : false;
+
+  if (!valid) {
+    if (pathname.startsWith("/api/")) {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
+    return NextResponse.redirect(new URL("/admin/login", request.url));
+  }
+
+  return NextResponse.next();
+}
+
+export const config = {
+  matcher: ["/admin/:path*", "/api/admin/:path*"],
+};