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>

internal/yandex/client.go

@@ -113,11 +113,6 @@ func WithRetryConfig(maxRetries int, baseBackoff, maxBackoff time.Duration, jitt
 
 // Do executes a Yandex API request with rate limiting, circuit breaking, and retry.
 func (c *Client) Do(ctx context.Context, method, path string, query map[string]string) (*Response, error) {
-	// Check circuit breaker
-	if !c.circuitBreaker.allow() {
-		return nil, fmt.Errorf("circuit breaker is open")
-	}
-
 	// Apply rate limiting
 	if err := c.rateLimiter.acquire(); err != nil {
 		return nil, fmt.Errorf("rate limit exceeded: %w", err)
@@ -129,8 +124,13 @@ func (c *Client) Do(ctx context.Context, method, path string, query map[string]s
 	var resp *Response
 	var err error
 
-	// Execute with retry
+	// Execute with retry, checking circuit breaker on each attempt
 	for attempt := 0; attempt <= c.retryConfig.maxRetries; attempt++ {
+		// Check circuit breaker on each retry attempt
+		if !c.circuitBreaker.allow() {
+			return nil, fmt.Errorf("circuit breaker is open")
+		}
+
 		resp, err = c.executeRequest(ctx, url)
 		if err == nil {
 			c.circuitBreaker.recordSuccess()