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/src/lib/db/index.ts

@@ -9,7 +9,7 @@ function createDb() {
   if (!url) {
     throw new Error("DATABASE_URL environment variable is not set");
   }
-  const client = postgres(url);
+  const client = postgres(url, { max: 5 });
   return drizzle({ client, schema });
 }