Train status is now coloured coded for your convenience

- Introduced TrainLateness enum to represent on-time, early, late (with minutes), and unknown states, including description text, color, and formatting logic.
- Replaced TrainStatusRow.status String with TrainLateness and update ContentView to render a colored status pill and to return TrainLateness from isOnTime.

Sources/AmtrakStatus/Models.swift

@@ -97,7 +97,7 @@ struct TrainStatusRow: Identifiable {
     var trainID: String
     var trainNum: String
     var routeName: String
-    var status: String
+    var status: TrainLateness
     var platform: String
     var arrival: String
     var departure: String