Wire NowPlayingStats to live aggregates: add SQL track duration column, stats endpoint, and duration backfill

DeepDrftPublic.Client/Helpers/RuntimeFormat.cs

@@ -0,0 +1,19 @@
+namespace DeepDrftPublic.Client.Helpers;
+
+/// <summary>
+/// Formats a runtime expressed in seconds as a compact <c>hh:mm</c> string for the home hero stat row.
+/// Hours are not zero-padded and may exceed two digits (mixes are few, so a large total simply renders
+/// "123:45"); minutes are always two digits. Negative or non-finite inputs clamp to "0:00".
+/// </summary>
+public static class RuntimeFormat
+{
+    public static string ToHoursMinutes(double totalSeconds)
+    {
+        if (double.IsNaN(totalSeconds) || double.IsInfinity(totalSeconds) || totalSeconds <= 0)
+            return "0:00";
+
+        var total = TimeSpan.FromSeconds(totalSeconds);
+        var hours = (int)total.TotalHours;
+        return $"{hours}:{total.Minutes:D2}";
+    }
+}