chore(deps): vendor the free-email domain list and drop unused packages

- vendor free-email-domains: its postinstall downloads a CDN CSV and
  overwrites its own domains.json, so the lockfile hash covers the
  tarball but not the installed data
- drop tailwind-merge and autoprefixer from apps/sim, which imports
  neither (emcn and docs declare their own tailwind-merge; postcss.config
  loads only tailwindcss)

Author: waleedlatif1