fix(vercel): add index.html and SPA rewrites to resolve 404 NOT_FOUND on Vercel

fix(vercel): add .vercelignore and function excludeFiles to prevent node_modules from inflating Python serverless zip

feat(monorepo): configure optimized fullstack Vercel monorepo deployment

fix(vercel): separate frontend build to bypass 500MB serverless bundle limit

fix(vercel): add npm install to buildCommand in vercel.json

fix(vercel): pin Python 3.11 and update pydantic version to resolve wheel compilation error

feat: configure Vercel Python serverless function handler for FastAPI backend

build: add root vercel.json for frontend deployment