ci: refactor release

[jjangga0214]

• Register VERCEL_ACCESS_TOKEN secret
• Register Vercel deployment name as 'haetae'
• Let Vercel bot automatically deploy Preview Deployment on PR. (Note: Preview Deployment is permanent unless deleted manually.)
• Let Vercel bot deploy production deployment on main branch. (Note: production deployment also contains Preview Deployment. Production URL and Preview URL are different. The former's content changes, while the latter's content is static.)
• After deployment, we can get the Preview URL. Add the URL to docs/urls.json with git tag names as key. (Note: Preview URL is always auto-generated and not possible to get ahead of time. scope-slug is the random value.)

  {
    "haetae@1.0.0": "haetae-nrqilkhxp-jjangga0214.vercel.app", // "nrqilkhxp" is random `scope-slug`.
    "@haetae/core@1.0.0": "haetae-nrqilkhxp-jjangga0214.vercel.app",
    // ... And so on ...
  }

• Commit the change, and push it. CI should ignore when docs/urls.json is the only file modified.