feat: implement MVP routing endpoints and cron station status detection

This commit implements the core routing functionality for the trip planner MVP:

1. API handlers for city autocomplete, station listing, route search, and route GeoJSON
2. Router integration with Yandex Schedules API for building routing graphs
3. Pareto-optimal route search with max 1 transfer and MCT filtering
4. Cron job for station status detection and closure monitoring
5. Circuit breaker and rate limiter integration in Yandex client
6. Redis cache-aside layer for city directories and station lists

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

cmd/cron/main.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"context"
+	"log"
+	"time"
+
+	"trip-planner/internal/cache"
+	"trip-planner/internal/yandex"
+)
+
+// stationStatusKey returns the Redis key for station status.
+func stationStatusKey(id string) *cache.CacheKey {
+	return &cache.CacheKey{
+		Kind: "station",
+		Code: id,
+	}
+}
+
+func main() {
+	ctx := context.Background()
+
+	// Initialize Redis cache
+	redisClient := cache.NewRedisCache(&cache.RedisConfig{
+		Addr:     "localhost:6379",
+		Password: "",
+		DB:       0,
+	})
+
+	// Initialize Yandex client
+	yandexClient := yandex.NewClient("test-key")
+
+	// Initialize station monitors for monitored stations
+	monitors := []*cron.StationMonitor{
+		{
+			ID:     "station-moscow-kiev",
+			Yandex: yandexClient,
+			Cache:  redisClient,
+		},
+		{
+			ID:     "station-petersburg-moscow",
+			Yandex: yandexClient,
+			Cache:  redisClient,
+		},
+	}
+
+	// Process all stations - this is the main cron job function
+	if err := cron.ProcessAllStations(ctx, monitors); err != nil {
+		log.Printf("ERROR: failed to process stations: %v", err)
+	}
+
+	// Log the status of all monitored stations
+	for _, monitor := range monitors {
+		statusKey := stationStatusKey(monitor.ID)
+		statusData, err := monitor.Cache.Get(ctx, statusKey)
+		if err == nil && statusData != nil {
+			log.Printf("INFO: station %s status: %s", monitor.ID, string(statusData))
+		}
+	}
+
+	log.Println("Cron job completed")
+}