Stop trusting the compromised eMudhra CA certificates #306

On 2026-10-20 it was disclosed that the private keys of eight eMudhra (emSign) intermediate CA certificates can be recovered by anyone; they chain to "emSign ECC Root CA - G3" and were cross-signed by Sectigo's "AAA Certificate Services" (https://emudhra.we-have-a-problem.com). In this repository, the /uk/chat/api/proxy Vercel Function forwards requests, including users' Authorization headers, to the Modal backend on a Node.js release that still trusts the emSign root, and the Modal backend and eval images can carry an unfixed ca-certificates package and certifi.

#305 removes both roots from Node's default CA list when the frontend's functions start, and refreshes ca-certificates and certifi in the Modal images.