Title: chore(deploy): Prepare production deployment, backups, and monitoring

Branch: chore/production-deploy

Goal: make the app safely hostable and maintainable

PR body:

## Why

A synced personal web app only becomes useful once it can be deployed reliably and operated with confidence.

## What changed

- added production settings and Vercel deployment configuration
- documented the Vercel hosting path for production and PR previews
- added health checks and baseline monitoring hooks
- documented database backup/restore expectations

## Acceptance criteria

- the repository documents a clear Vercel deployment path for production and PR previews
- production configuration is separated from local development
- backup and restore steps are defined

## Out of scope

- new product features
- advanced analytics

Prompt for GitHub Copilot:

Read README.md and .github/copilot-instructions.md first.

Create a new GitHub Issue for deployment readiness, then create branch chore/production-deploy and implement only this PR.

Prepare the app for real hosting:
- production-safe Django settings
- deployment config for Vercel production and PR preview environments
- health checks
- monitoring/logging hooks
- backup and restore documentation for PostgreSQL

Keep this PR operational in scope. Do not add new end-user features. Update docs thoroughly, add validation where possible, and use scoped commit messages with the issue number before opening the PR with the planned title and body.