Add Stripe payment integration for AI subscriptions
Implement subscription-based AI access with 250 generations/month at $5/month or $50/year.
Changes:
- Backend: Stripe service, payment routes, webhook handlers, generation tracking
- Frontend: Upgrade page with pricing, payment success/cancel pages, UI prompts
- Database: Add subscription fields to users, payments table, migrations
- Config: Stripe env vars to .env.example, docker-compose.prod.yml, PRODUCTION.md
- Tests: Payment route tests, component tests, subscription hook tests
Users without AI access see upgrade prompts; subscribers see remaining generation count.
Joey Yakimowich-Payne
2e12edc249