[Draft] Bootstrap initial Vercel deployment path

[BASIC-BIT]

Problem

VRDex has a locked frontend deployment direction (Vercel), but there is not yet a concrete deployment/bootstrap path for the initial app.

Scope

• define the minimum repo/app setup needed for initial Vercel deployment
• configure the project so the initial Next.js app can be deployed in a basic preview/hosted mode
• document the minimum required environment/config expectations for that deployment path
• keep the setup compatible with later Convex, auth, billing, and docs integration

Non-goals

• full production hardening
• complete environment/secrets strategy for every future service
• self-hosting implementation
• AWS infrastructure implementation
• Stripe production billing setup
• advanced CI/CD pipeline work

Acceptance criteria

• there is a documented and practical first-pass Vercel deployment path for the app
• the initial app can be deployed in a basic hosted mode once the app scaffold exists
• required environment/config expectations are explicit
• the setup does not prematurely lock the repo into hosted-only assumptions

Likely docs to update

• README.md
• docs/planning/engineering-strategy.md
• docs/README.md
• any deployment/bootstrap doc created during implementation

Soft dependencies

• #53 Scaffold initial Next.js web app
• likely #55 Wire initial Next.js app to Convex backend if deployed with live backend wiring

Soft dependents

• #18 Implement multi-provider account login for v0.5 (Discord, Google, email/password), if hosted callback URLs are needed early
• preview-based UI verification work
• follow-on infra/self-hosting posture work (#42)