Vale construir sua versão de Playpass?

Build a self-hosted league registration and scheduling app for a single organizer running recreational sports leagues.

Stack, no substitutions:
- Next.js 15 with App Router and TypeScript
- SQLite via Prisma, file at ./data/app.db
- Tailwind CSS, plain and boring, no component library
- Stripe Checkout in test mode for payments
- Resend for transactional email, fall back to logging emails to console if RESEND_API_KEY is missing
- Single admin password from ADMIN_PASSWORD in .env, session cookie, no user accounts for admins

Data model: League (name, sport, season dates, fee in cents, capacity, public slug, status), Registration (name, email, phone, notes, waiverAcceptedAt, paymentStatus, stripeSessionId), Team, TeamMember, Game (round, date, homeTeam, awayTeam, homeScore, awayScore).

Public side:
- /l/[slug] shows league info, remaining spots, and a registration form
- Submitting creates a pending Registration and redirects to Stripe Checkout
- Webhook at /api/stripe/webhook marks the registration paid and emails a confirmation
- If the league is at capacity, put the registration on a waitlist instead of charging
- /l/[slug]/schedule shows the generated schedule and a standings table computed from entered scores

Admin side at /admin:
- Create and edit leagues, view registrations with payment status, export CSV
- Manually mark a registration paid or refunded, no Stripe refund API call, just a status field and a note
- Auto-assign paid registrations into N teams, allow drag-free manual reassignment via a dropdown per player
- Generate a round robin schedule across a list of date slots, regenerate wipes and rebuilds
- Enter scores per game, standings recompute from wins, losses, ties and point differential

Explicitly out of scope: refunds through Stripe, discount codes, installment payments, a mobile app, push notifications, multi-organizer permissions, analytics, telemetry.

All secrets in .env, provide .env.example with DATABASE_URL, ADMIN_PASSWORD, STRIPE_SECRET_KEY, STRIPE_WEBHOOK_SECRET, RESEND_API_KEY. Include a seed script that creates one league with twenty paid registrations so the schedule and standings pages have something to show. README covers local run, Stripe CLI webhook forwarding, and one loud warning that taking real money means real refund and tax obligations.