Vercel CLI (`vercel`)

Vercel CLI cookbook for this Next.js + Supabase + Vercel boilerplate. Covers deployment verification (poll by commit SHA + `vercel inspect --wait`), env var sync between `.env` and Vercel scopes (Preview / Production / Development), build and runtime log streaming, rollback, and `.vercel/` project linking detection. Trigger whenever the user runs `vercel`, asks to "check deploy status", "wait until ready", "is my deploy live", "sync env vars to Vercel", "push env to Vercel", "see build logs", "tail Vercel logs", "rollback last deploy", "promote to production", "link this repo to Vercel", or any vercel-CLI-shaped task. Composes with `/deploy-to-vercel` (community skill, ow…