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/api/cron/late-fees/route.ts

@@ -0,0 +1,69 @@
+import { NextResponse } from "next/server"
+import { and, eq, lte } from "drizzle-orm"
+import { db } from "@/lib/db"
+import { rent_payments, expenses } from "@/lib/db/schema"
+import { isAuthorizedCron } from "@/lib/cron-auth"
+
+// Vercel Cron: runs daily at 8am (see vercel.json)
+export async function GET(request: Request) {
+  if (!isAuthorizedCron(request)) {
+    return NextResponse.json({ error: "Unauthorized" }, { status: 401 })
+  }
+
+  // Find overdue payments older than grace period (default 5 days) that don't yet have a late fee
+  const graceDays = 5
+  const cutoff = new Date()
+  cutoff.setDate(cutoff.getDate() - graceDays)
+  const cutoffDate = cutoff.toISOString().slice(0, 10)
+
+  const overduePayments = await db
+    .select({
+      id: rent_payments.id,
+      user_id: rent_payments.user_id,
+      tenant_id: rent_payments.tenant_id,
+      property_id: rent_payments.property_id,
+      unit_id: rent_payments.unit_id,
+      amount: rent_payments.amount,
+      due_date: rent_payments.due_date,
+    })
+    .from(rent_payments)
+    .where(
+      and(
+        eq(rent_payments.status, "overdue"),
+        lte(rent_payments.due_date, cutoffDate),
+        eq(rent_payments.late_fee_applied, false)
+      )
+    )
+
+  if (!overduePayments.length) {
+    return NextResponse.json({ processed: 0 })
+  }
+
+  let processed = 0
+
+  for (const payment of overduePayments) {
+    const lateFeeAmount = Math.round(Number(payment.amount) * 0.05 * 100) / 100 // 5% late fee
+
+    // Insert late fee as a separate expense
+    await db.insert(expenses).values({
+      user_id:      payment.user_id,
+      property_id:  payment.property_id,
+      unit_id:      payment.unit_id ?? null,
+      category:     "other",
+      description:  `Late fee — rent due ${payment.due_date}`,
+      amount:       lateFeeAmount,
+      expense_date: new Date().toISOString().slice(0, 10),
+      vendor:       "Auto-generated",
+    })
+
+    // Mark late fee applied
+    await db
+      .update(rent_payments)
+      .set({ late_fee_applied: true })
+      .where(eq(rent_payments.id, payment.id))
+
+    processed++
+  }
+
+  return NextResponse.json({ processed, message: `Applied late fees to ${processed} overdue payment(s).` })
+}