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

DeepDrftPublic.Client/Startup.cs

@@ -26,6 +26,10 @@ public static class Startup
         services.AddScoped<ReleaseDetailViewModel>();
         services.AddScoped<CutDetailViewModel>();
 
+        // Home hero stats read surface — same HTTP posture as the track/release clients.
+        services.AddScoped<StatsClient>();
+        services.AddScoped<IStatsDataService, StatsClientDataService>();
+
         // Waveform visualizer controls — scoped so the eight slider positions persist across navigation
         // within a session and reset on a fresh page load (see WaveformVisualizerControlState).
         services.AddScoped<WaveformVisualizerControlState>();