- add per-request timeout to the Sheets fetch so a hung call can't block /sync
- stop leaking raw sync errors to chat; log detail, reply generically
- migrate logging from log to structured log/slog
- drop duplicate godotenv.Load from ReadSheet (LoadConfig loads .env at startup)
- add multi-stage distroless Dockerfile + .dockerignore; embed tzdata via import
- document single-instance long-polling constraint in README
- translate sheet.go comments to English
- move package doc to doc.go; remove superseded root main.go and live_test.go
Add Reminder that posts a weekly cleaning-duty reminder to a Telegram
group on a configurable schedule (REMINDER_WEEKDAY/REMINDER_HOUR), in
Europe/Warsaw time, announcing the duty DUTY_AHEAD_DAYS out. Reminders
are disabled unless GROUP_CHAT_ID is set. Wire ReminderConfig parsing
into LoadConfig with validation, document the commands and reminder
config in README, and cover config loading with tests.