fix: switch to static export and nginx for reliable CSS serving

Node-based static servers (serve, http-server) were returning 404 for
CSS files. Switched to output: "export" in Next.js config and nginx
as the production static file server.

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

ecosystem.config.js

@@ -2,9 +2,9 @@ module.exports = {
   apps: [
     {
       name: "cronicas-de-los-reinos",
+      script: "serve",
+      args: "out -l 3000 --no-clipboard",
       cwd: "/home/PaginaNovelasYRpg",
-      script: "node_modules/.bin/next",
-      args: "start -H 0.0.0.0 -p 3000",
       env: {
         NODE_ENV: "production",
       },