feat(phase-16.3): light up anonId unique-listener layer

Mint a first-party localStorage anonId, thread it onto play/share beacons,
persist it via EventController, and add all-time distinct-listener counts
(site/track/release). Storage columns + indexes already existed from 16.1.

DeepDrftTests/ShareTrackerTests.cs

@@ -34,12 +34,24 @@ public class ShareTrackerTests
         protected override void NavigateToCore(string uri, bool forceLoad) { }
     }
 
+    // Fixed-value anon-id provider so the tracker can attach a token without JS interop. Treated as
+    // already warmed (Current returns the value); EnsureLoadedAsync is a no-op here.
+    private sealed class StubAnonIdProvider : IAnonIdProvider
+    {
+        public StubAnonIdProvider(string? current) => Current = current;
+        public string? Current { get; }
+        public ValueTask EnsureLoadedAsync() => ValueTask.CompletedTask;
+    }
+
     private ShareTracker _tracker = null!;
     private readonly DateTimeOffset _t0 = new(2026, 6, 19, 12, 0, 0, TimeSpan.Zero);
 
     [SetUp]
     public void SetUp()
-        => _tracker = new ShareTracker(new BeaconInterop(new NoopJsRuntime()), new TestNavigationManager());
+        => _tracker = new ShareTracker(
+            new BeaconInterop(new NoopJsRuntime()),
+            new StubAnonIdProvider("anon-1"),
+            new TestNavigationManager());
 
     // A copy-link records one share with channel = link.
     [Test]