feat(stats): flip home Plays card live (Phase 16.5)

Add TotalPlays + UniqueListeners to HomeStatsDto, composed at
StatsController from IEventService (no migration). Card reads via
existing persistent-state-bridged round-trip.

DeepDrftData/IEventService.cs

@@ -21,6 +21,13 @@ public interface IEventService
     /// <summary>Record one share: append a <c>share_event</c> row. Target and channel come straight from the client.</summary>
     Task<Result> RecordShare(ShareTargetType targetType, string targetKey, ShareChannel channel, string? anonId = null, CancellationToken cancellationToken = default);
 
+    /// <summary>
+    /// Site-wide total play count (Phase 16 §5 — all-time): the sum of every <c>play_counter</c> row's
+    /// three bucket columns. Zero until the telemetry migration is applied. The home Plays card's primary
+    /// figure; the controller composes it onto <c>HomeStatsDto</c> alongside the track-domain figures.
+    /// </summary>
+    Task<ResultContainer<long>> GetTotalPlayCount(CancellationToken cancellationToken = default);
+
     /// <summary>
     /// Site-wide distinct-listener count (Phase 16 §3, D3 — all-time): distinct non-null <c>anon_id</c>
     /// values across all play events. Null tokens are excluded (not a known listener). The capability for