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.

DeepDrftPublic.Client/Startup.cs

@@ -38,8 +38,11 @@ public static class Startup
         // Phase 16 anonymous telemetry (client side). BeaconInterop wraps sendBeacon; the play sink and
         // share tracker fire events through it. The play tracker itself is NOT registered — the player
         // is not DI-registered, so AudioPlayerProvider constructs the tracker and attaches it. ShareTracker
-        // is scoped so its per-(target,channel) debounce memory lives for the session.
+        // is scoped so its per-(target,channel) debounce memory lives for the session. AnonIdProvider
+        // (wave 16.3) caches the first-party localStorage listener id; scoped so the cache lives for the
+        // session, warmed when a surface goes interactive (the player provider, the share popover).
         services.AddScoped<BeaconInterop>();
+        services.AddScoped<IAnonIdProvider, AnonIdProvider>();
         services.AddScoped<IPlayEventSink, BeaconPlayEventSink>();
         services.AddScoped<ShareTracker>();
     }