- Add startup env validation that fails fast in production if critical vars
(JWT_SECRET, JWT_REFRESH_SECRET, DATABASE_URL, CORS_ORIGINS, REDIS_HOST)
are missing
- Fix CORS_ORIGINS to throw in production instead of defaulting to localhost
- Replace hardcoded dev passwords in .env.example with CHANGE_ME placeholders
- Add missing vars to .env.example (CORS_ORIGINS, SMTP_*, FIREBASE, LOG_LEVEL)
- Warn on missing optional payment/storage vars at startup
Co-Authored-By: Paperclip <noreply@paperclip.ing>