Security hardening from 2026-07-01 audit

- Exclude supabase/ from Docker build context (leaked service_role key file)
- /api/files: exact per-user namespace match + reject path traversal;
  storage resolveKey rejects ".."/"." segments (fixes cross-user file read)
- Add ownsProperty/Unit/Tenant checks to tenants, maintenance (landlord path),
  and documents (JSON branch, now field-whitelisted) create handlers
- Escape user data in follow-up + payment-link emails (reuse escapeHtml)
- Neutralize CSV formula injection in toCsv + export routes
- Tighter sign-in rate limit (10/min); env-gated email verification + sender
- Per-request nonce CSP; drop script-src 'unsafe-inline' (styles unchanged)
- Add input length bounds; validate follow-ups POST body

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

next.config.ts

@@ -1,22 +1,9 @@
 import type { NextConfig } from "next";
 
-// Pragmatic baseline Content-Security-Policy for a Next.js app.
-// NOTE: Next 16 commonly needs 'unsafe-inline' for styles/scripts when no
-// nonce pipeline is configured. Tightening this to per-request nonces
-// (removing 'unsafe-inline') is a recommended follow-up.
-const contentSecurityPolicy = [
-  "default-src 'self'",
-  "img-src 'self' data: blob: https:",
-  "style-src 'self' 'unsafe-inline'",
-  "script-src 'self' 'unsafe-inline'",
-  "font-src 'self' data:",
-  "connect-src 'self' https://api.stripe.com https://api.openai.com https://api.resend.com",
-  "frame-src https://js.stripe.com https://hooks.stripe.com",
-  "frame-ancestors 'none'",
-  "base-uri 'self'",
-  "form-action 'self'",
-].join("; ");
-
+// NOTE: The Content-Security-Policy is set per-request in `proxy.ts` (Next
+// middleware) so `script-src` can carry a per-request nonce instead of
+// 'unsafe-inline'. A static header here cannot carry a per-request nonce and
+// would conflict with the middleware, so it is intentionally omitted below.
 const nextConfig: NextConfig = {
   // Emit a self-contained server bundle at .next/standalone so the Docker
   // image (used by Coolify) ships only the files needed to run `node server.js`.
@@ -38,7 +25,6 @@ const nextConfig: NextConfig = {
             value: "max-age=63072000; includeSubDomains; preload",
           },
           { key: "X-DNS-Prefetch-Control", value: "off" },
-          { key: "Content-Security-Policy", value: contentSecurityPolicy },
         ],
       },
     ];