[P0.7] Vercel production deployment and authentication URL registration

### Goal
Deploy JuanProperty to Vercel production, configure environment variables, register canonical production domain in Supabase Auth redirect URLs and Google OAuth authorized origins, and verify live authentication.

### Dependencies
[P0.1], [P0.2], [P0.3], [P0.4], [P0.6]

### Acceptance Criteria
- Clean build and deploy on Vercel
- Canonical HTTPS domain active
- Production auth redirect URLs verified end-to-end

### Run
`/setup-vercel`

Start with the `/setup-vercel` entry point and review dependencies [P0.1], [P0.2], [P0.3], [P0.4], and [P0.6]. Configure the Vercel environment and production domain, register the domain in Supabase Auth and Google OAuth, then verify a clean deployment and end-to-end production authentication.

Written by the indexing model from the issue text.