fix: corregir ruteo de job-status y encoding de job_id en Vercel

feat: reestructuracion produccion nube (Vercel + RunPod Serverless GPU)

fix: corregir error de sintaxis ESM/CJS en frontend/api/generate-2d.js

fix: place serverless api function inside frontend/api for Vercel root directory

config: add vercel.json rewrite rules for serverless API