fix: address code review findings

cmd/api/handlers.go

@@ -205,6 +205,18 @@ func RouteSearch(hc *HandlerContext, w http.ResponseWriter, r *http.Request) {
 		RankingMode: rankingMode,
 	}
 
+	// Determine if this is a far-term search (date is more than 7 days in the future)
+	if req.Date != "" {
+		requestDate, err := time.Parse("2006-01-02", req.Date)
+		if err == nil {
+			now := time.Now()
+			daysDiff := int(requestDate.Sub(now).Hours() / 24)
+			if daysDiff >= 7 {
+				opts.FarTerm = true
+			}
+		}
+	}
+
 	// Detect closed stations and get neighbors for fallback
 	closedStationsMap := make(map[string]bool)
 	neighborsMap := make(map[string][]storage.StationNeighbor)
@@ -431,7 +443,7 @@ func StationStatus(hc *HandlerContext, w http.ResponseWriter, r *http.Request) {
 func adminAuth(hc *HandlerContext, w http.ResponseWriter, r *http.Request) bool {
 	expectedAPIKey := os.Getenv("TRIP_PLANNER_ADMIN_API_KEY")
 	if expectedAPIKey == "" {
-		http.Error(w, "unauthorized", http.StatusUnauthorized)
+		http.Error(w, "server configuration error: TRIP_PLANNER_ADMIN_API_KEY is not set", http.StatusInternalServerError)
 		return false
 	}
 	providedAPIKey := r.Header.Get("X-Admin-Api-Key")