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/vendors/[id]/route.ts

@@ -0,0 +1,46 @@
+import { NextResponse } from "next/server"
+import { and, eq } from "drizzle-orm"
+import { db } from "@/lib/db"
+import { vendors } from "@/lib/db/schema"
+import { getSessionUser } from "@/lib/session"
+import { ownsProperty } from "@/lib/db/ownership"
+
+export async function PATCH(request: Request, { params }: { params: Promise<{ id: string }> }) {
+  const user = await getSessionUser()
+  if (!user) return NextResponse.json({ error: "Unauthorized" }, { status: 401 })
+
+  const { id } = await params
+  const body = await request.json()
+
+  const allowed: Partial<typeof vendors.$inferInsert> = {}
+  if (body.name !== undefined) allowed.name = body.name
+  if (body.trade !== undefined) allowed.trade = body.trade || null
+  if (body.phone !== undefined) allowed.phone = body.phone || null
+  if (body.email !== undefined) allowed.email = body.email || null
+  if (body.notes !== undefined) allowed.notes = body.notes || null
+  if (body.property_id !== undefined) allowed.property_id = body.property_id || null
+
+  if (!(await ownsProperty(user.id, allowed.property_id))) {
+    return NextResponse.json({ error: "Invalid reference" }, { status: 403 })
+  }
+
+  try {
+    const [data] = await db
+      .update(vendors)
+      .set(allowed)
+      .where(and(eq(vendors.id, id), eq(vendors.user_id, user.id)))
+      .returning()
+
+    return NextResponse.json(data)
+  } catch (e) {
+    return NextResponse.json({ error: (e as Error).message }, { status: 500 })
+  }
+}
+
+export async function DELETE(_: Request, { params }: { params: Promise<{ id: string }> }) {
+  const user = await getSessionUser()
+  if (!user) return NextResponse.json({ error: "Unauthorized" }, { status: 401 })
+  const { id } = await params
+  await db.delete(vendors).where(and(eq(vendors.id, id), eq(vendors.user_id, user.id)))
+  return NextResponse.json({ ok: true })
+}