Fix Payload CMS deploy on Vercel + build a multi-edition magazine model (Next.js)

We're building a self-hosted Payload CMS (v3) so our team can create and edit multiple magazine "editions" ourselves. The project is already started and hosted on Vercel with a Postgres database — we need an experienced Payload/Next.js developer to take it the rest of the way. The work, in two phases: Phase 1 (small, do first): Finish the initial deployment so the Payload admin loads and we can log in. There's a build issue on the current setup we'll walk you through on hire. Phase 2 (follow-on): Build the CMS structure for a multi-edition magazine — editions, pages, reusable content blocks, a shared "decor" catalog, media, and editor roles — and connect a front-end that renders the editions. We'll provide the visual design to work from. You should have: Proven Payload CMS v3 experience (please link real projects) Next.js (App Router), TypeScript, and Vercel deployment experience PostgreSQL, and strong build/deployment debugging skills