Initial import: property management SaaS + security hardening + admin dashboard

Property Management Network — Next.js 16 (App Router), Better Auth,
Drizzle ORM over PostgreSQL, Stripe, OpenAI, Resend.

Includes:
- Security hardening: access-control/IDOR fixes, TLS-by-default DB layer,
  constant-time cron auth, strict security headers, atomic AI quota gating,
  HTML/email output encoding, demo-backdoor disabled in production.
- Superadmin dashboard at /admin (overview/MRR, server-paginated users with
  ban/impersonate/plan/delete, billing, platform activity + admin audit log,
  AI usage, system health) via the Better Auth admin plugin.
- Seed/migration utility scripts under scripts/.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/robots.txt/route.ts

@@ -0,0 +1,20 @@
+export async function GET() {
+  const appUrl = process.env.NEXT_PUBLIC_APP_URL ?? "https://propertymanagement.network"
+  const body = `User-agent: *
+Allow: /
+Disallow: /dashboard
+Disallow: /properties
+Disallow: /tenants
+Disallow: /rent
+Disallow: /maintenance
+Disallow: /leases
+Disallow: /expenses
+Disallow: /settings
+Disallow: /api/
+
+Sitemap: ${appUrl}/sitemap.xml`
+
+  return new Response(body, {
+    headers: { "Content-Type": "text/plain" },
+  })
+}