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.

DeepDrftTests/PlayEventQueryTests.cs

@@ -159,6 +159,45 @@ public class PlayEventQueryTests
         Assert.That(await _context.PlayCounters.AnyAsync(c => c.TrackId == track.Id), Is.False);
     }
 
+    // --- Site-wide total plays (§5 — the home Plays card's primary figure) ---
+
+    // An empty counter table sums to zero rather than throwing — the card's reading until the
+    // telemetry migration is applied and the first play lands.
+    [Test]
+    public async Task CountTotalPlaysAsync_NoCounters_IsZero()
+    {
+        Assert.That(await CreateRepository().CountTotalPlaysAsync(), Is.EqualTo(0L));
+    }
+
+    // Total plays sums all three bucket columns of a single track's counter.
+    [Test]
+    public async Task CountTotalPlaysAsync_SumsAllBucketsOfOneCounter()
+    {
+        await SeedTrackAsync("track-1");
+        var repo = CreateRepository();
+        await repo.RecordPlayAsync("track-1", PlayBucket.Partial, null);
+        await repo.RecordPlayAsync("track-1", PlayBucket.Sampled, null);
+        await repo.RecordPlayAsync("track-1", PlayBucket.Sampled, null);
+        await repo.RecordPlayAsync("track-1", PlayBucket.Complete, null);
+
+        Assert.That(await repo.CountTotalPlaysAsync(), Is.EqualTo(4L));
+    }
+
+    // Total plays is site-wide: it sums across every track's counter, not one track's.
+    [Test]
+    public async Task CountTotalPlaysAsync_SumsAcrossAllTracks()
+    {
+        await SeedTrackAsync("track-1");
+        await SeedTrackAsync("track-2");
+        var repo = CreateRepository();
+        await repo.RecordPlayAsync("track-1", PlayBucket.Complete, null);
+        await repo.RecordPlayAsync("track-1", PlayBucket.Partial, null);
+        await repo.RecordPlayAsync("track-2", PlayBucket.Sampled, null);
+
+        Assert.That(await repo.CountTotalPlaysAsync(), Is.EqualTo(3L),
+            "site-wide total spans every track's counter");
+    }
+
     // A share append writes one row with the target, channel, and a null anonId.
     [Test]
     public async Task RecordShareAsync_AppendsRow()