feat: 增加晚点未定功能

CRSim.Core/Models/Simulator/TrainStatus.cs

@@ -0,0 +1,14 @@
+namespace CRSim.Core.Models
+{
+    public static class TrainStatus
+    {
+        // 00:00:01 is reserved for "delay unknown"; normal input/export paths only use minute precision.
+        public static readonly TimeSpan DelayUnknown = TimeSpan.FromSeconds(1);
+
+        public static bool IsDelayUnknown(TimeSpan? status) =>
+            status.HasValue && status.Value == DelayUnknown;
+
+        public static TimeSpan GetScheduleOffset(TimeSpan? status) =>
+            IsDelayUnknown(status) ? TimeSpan.Zero : status ?? TimeSpan.Zero;
+    }
+}