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/files/[...key]/route.ts

@@ -0,0 +1,41 @@
+import { NextResponse } from "next/server"
+import { getSessionUser } from "@/lib/session"
+import { readFile, contentTypeForKey } from "@/lib/storage"
+
+// Only these image types are safe to render inline from our origin. Everything
+// else (including svg, html, documents) is forced to download as an attachment.
+const INLINE_EXTENSIONS = ["png", "jpg", "jpeg", "gif", "webp"]
+
+// Auth-gated file serving. Storage keys are namespaced by user id
+// (`<userId>/<scope>/<file>`), so a file belongs to the requester iff the key's
+// first segment equals their session user id.
+export async function GET(_: Request, { params }: { params: Promise<{ key: string[] }> }) {
+  const user = await getSessionUser()
+  if (!user) return NextResponse.json({ error: "Unauthorized" }, { status: 401 })
+
+  const { key: segments } = await params
+  const key = segments.map((s) => decodeURIComponent(s)).join("/")
+
+  if (!key.startsWith(`${user.id}/`)) {
+    return NextResponse.json({ error: "Forbidden" }, { status: 403 })
+  }
+
+  try {
+    const buffer = await readFile(key)
+
+    const ext = key.split(".").pop()?.toLowerCase() ?? ""
+    const disposition = INLINE_EXTENSIONS.includes(ext) ? "inline" : "attachment"
+    const basename = (key.split("/").pop() ?? "file").replace(/["\\\r\n\x00-\x1f]/g, "")
+
+    return new NextResponse(new Uint8Array(buffer), {
+      headers: {
+        "Content-Type": contentTypeForKey(key),
+        "Content-Disposition": `${disposition}; filename="${basename}"`,
+        "X-Content-Type-Options": "nosniff",
+        "Cache-Control": "private, max-age=3600",
+      },
+    })
+  } catch {
+    return NextResponse.json({ error: "Not found" }, { status: 404 })
+  }
+}