Full app rebuild: FastAPI backend + React Native mobile with auth, championships, admin

Backend (FastAPI + SQLAlchemy + SQLite):
- JWT auth with access/refresh tokens, bcrypt password hashing
- User model with member/organizer/admin roles, auto-approve members
- Championship, Registration, ParticipantList, Notification models
- Alembic async migrations, seed data with test users
- Registration endpoint returns tokens for members, pending for organizers
- /registrations/my returns championship title/date/location via eager loading
- Admin endpoints: list users, approve/reject organizers

Mobile (React Native + Expo + TypeScript):
- Zustand auth store, Axios client with token refresh interceptor
- Role-based registration (Member vs Organizer) with contextual form labels
- Tab navigation with Ionicons, safe area headers, admin tab for admin role
- Championships list with status badges, detail screen with registration progress
- My Registrations with championship title, progress bar, and tap-to-navigate
- Admin panel with pending/all filter, approve/reject with confirmation
- Profile screen with role badge, Ionicons info rows, sign out
- Password visibility toggle (Ionicons), keyboard flow hints (returnKeyType)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

start-backend.bat

@@ -0,0 +1,4 @@
+@echo off
+echo Starting Pole Championships backend...
+cd /d "%~dp0backend"
+.venv\Scripts\python -m uvicorn app.main:app --host 0.0.0.0 --port 8000 --reload