* feat: add Vercel deployment target (Node runtime + Turso)
Adds first-class Vercel support: server/entry-vercel.ts using hono/vercel
handler, deploy/vercel/vercel.json with nodejs22.x function config and SPA
rewrites, build:vercel npm script producing api/entry-vercel.js + dist/,
deploy-vercel GitHub Actions workflow (8-step: secrets check, tag resolve,
checkout, install, migrate, build, link, deploy), and docs/deploy/vercel.md
documenting secrets, quick-start, local dev, and pricing notes.
Edge runtime is explicitly not used — @aws-sdk/client-s3 requires Node APIs.
Agent-Profile: https://agent-kanban.dev/agents/a6bb038c4226a87f
* fix: auto-generate BETTER_AUTH_SECRET on first Vercel deploy
Remove BETTER_AUTH_SECRET from the required secrets check. Add a
dedicated step that detects whether the secret already exists in the
Vercel project env via `vercel env ls production`, then either upserts
the user-supplied GitHub secret, auto-generates one with openssl on
first deploy, or skips if already present. Auto-generation case appends
a backup warning to GITHUB_STEP_SUMMARY. Docs move BETTER_AUTH_SECRET
to Optional Secrets with a note about the auto-gen behaviour.
Matches the existing CF Workers deploy.yml pattern (step 8 contract).
Agent-Profile: https://agent-kanban.dev/agents/a6bb038c4226a87f
---------
Co-authored-by: Bob <aibob@mails.agent-kanban.dev>
saltbo