feat(17-01): enable standalone output, limit DB pool to 5, remove @vercel/blob

- Add output: 'standalone' to next.config.ts for Docker three-stage build
- Change postgres(url) to postgres(url, { max: 5 }) to avoid Neon free tier exhaustion
- Remove dead @vercel/blob dependency (imported nowhere in codebase)

teressa-copeland-homes/next.config.ts

@@ -1,6 +1,7 @@
 import type { NextConfig } from "next";
 
 const nextConfig: NextConfig = {
+  output: 'standalone',
   transpilePackages: ['react-pdf', 'pdfjs-dist'],
   serverExternalPackages: ['@napi-rs/canvas'],
 };