fix(input): correct lon mapping

internal/engine/models.go

@@ -1,7 +1,9 @@
 package engine
 
 import (
+	"fmt"
 	"sort"
+	"time"
 
 	"predictor-refactored/internal/numerics"
 	"predictor-refactored/internal/weather"
@@ -84,6 +86,11 @@ func WindTransport(field weather.WindField, events *EventSink) Model {
 	return func(t float64, s State) numerics.Rate {
 		sample, err := field.Wind(t, s.Lat, s.Lng, s.Altitude)
 		if err != nil {
+			// Recorded, not swallowed. A zero rate here is indistinguishable
+			// from calm air, so returning one turns "we have no data for this
+			// time" into "the balloon did not move" — see EventSink.Fail.
+			events.Fail(fmt.Errorf("no wind data at %s: %w",
+				time.Unix(int64(t), 0).UTC().Format(time.RFC3339), err))
 			return numerics.Rate{}
 		}
 		if sample.AboveModel && events != nil {