- Create cmd/cron/station_status.go with daily station status checking
- Implement schedule querying via Yandex API with rate limiting and circuit breaker
- Closure detection: N consecutive days of zero trips (N=3) → closed status
- Reactivation: active status when trips resume after being closed
- Add tests for cron logic: status transition, zero-flight detection, reactivation
- All tests pass: go test ./cmd/cron/ and go test ./...
