Add SQLite visitor IP logging to /server_storage

Log visitor IPs and paths to a local SQLite database via the existing
analytics API route, persisted at /server_storage/visitors.db in Docker
(falls back to ./visitors.db in dev).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

next.config.ts

@@ -2,7 +2,7 @@ import type { NextConfig } from "next";
 
 const nextConfig: NextConfig = {
   output: "standalone",
-  /* config options here */
+  serverExternalPackages: ['better-sqlite3'],
   headers: async () => {
     return [
       {