fix: address code review findings

- Fix type mismatch in search_cache.go: SearchWithCache now returns *yandex.Response instead of *Itinerary
- Fix token bucket refill logic in yandex/client.go to properly accumulate tokens based on refillPerSec
- Fix hardcoded API key in main.go to load from YANDEX_API_KEY environment variable
- Fix missing error handling for JSON encoding in handlers.go RouteGeoJSON function
- Fix incorrect redis.Nil handling in cache/store.go CacheAside.Exists method
- Fix incorrect error return type in station_status.go updateStationStatus to return newStatus instead of empty string

cmd/cron/station_status.go

@@ -175,22 +175,22 @@ func (sm *StationMonitor) updateStationStatus(ctx context.Context, tripCount int
 
 	// Write updated status to cache with 24h TTL
 	if err := sm.Cache.Set(ctx, cacheKey, []byte(newStatus), 24*time.Hour); err != nil {
-		return "", fmt.Errorf("cache set status: %w", err)
+		return newStatus, fmt.Errorf("cache set status: %w", err)
 	}
 
 	// Write updated zero days count to cache with 24h TTL
 	if err := sm.Cache.Set(ctx, zeroDaysKey, []byte(fmt.Sprintf("%d", zeroDays)), 24*time.Hour); err != nil {
-		return "", fmt.Errorf("cache set zero days: %w", err)
+		return newStatus, fmt.Errorf("cache set zero days: %w", err)
 	}
 
 	// Write updated zero-since timestamp to cache with 24h TTL
 	if err := sm.Cache.Set(ctx, zeroSinceKey, []byte(fmt.Sprintf("%d", zeroSince.Unix())), 24*time.Hour); err != nil {
-		return "", fmt.Errorf("cache set zero since: %w", err)
+		return newStatus, fmt.Errorf("cache set zero since: %w", err)
 	}
 
 	// Write updated last-seen-flight timestamp to cache with 24h TTL
 	if err := sm.Cache.Set(ctx, lastSeenFlightKey, []byte(fmt.Sprintf("%d", lastSeenFlight.Unix())), 24*time.Hour); err != nil {
-		return "", fmt.Errorf("cache set last seen flight: %w", err)
+		return newStatus, fmt.Errorf("cache set last seen flight: %w", err)
 	}
 
 	return newStatus, nil