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

DeepDrftPublic.Client/Services/IStatsDataService.cs

@@ -0,0 +1,15 @@
+using DeepDrftModels.DTOs;
+using NetBlocks.Models;
+
+namespace DeepDrftPublic.Client.Services;
+
+/// <summary>
+/// Home-stats read abstraction. Both SSR and WASM renders are served by <c>StatsClientDataService</c>
+/// in this assembly, which delegates to <see cref="Clients.StatsClient"/> over HTTP. Components inject
+/// this single seam so they do not branch on render mode — mirrors <see cref="IReleaseDataService"/>.
+/// </summary>
+public interface IStatsDataService
+{
+    /// <summary>Aggregate figures behind the public home hero stat row, in one round-trip.</summary>
+    Task<ApiResult<HomeStatsDto>> GetHomeStats();
+}