Fix vercel dev local orchestration and API routing

[MD2SA]

The Problem

pnpm dev (concurrent backend/frontend) works but lacks production parity. vercel dev currently fails to emulate the Vercel environment correctly, causing a gap between local development and production.

Specific Issues

• Routing: /api/* requests are not being proxied to the /api directory serverless functions.
• Initialization: Python functions fail to boot within the Vercel local emulator.
• Proxy Conflict: Collision between Vite’s dev server port and Vercel’s proxy port.
• Env Injection: Environment variables from .env are not consistently passed to the Python runtime under vercel dev.

Goal

Achieve 1:1 parity between local development and production deployment.