fix(telemetry): first-party fetch for play/share, beacon only on unload

Route normal play closes (end/switch/stop) and all shares through a same-origin
HttpClient POST so privacy-hardened browsers stop blocking them; keep sendBeacon
for the tab-unload edge. Rename the JS module off telemetry/beacon to session/
lifecycle so the retained fallback isn't name-matched. No new data or identifiers.

DeepDrftPublic.Client/Startup.cs

@@ -42,12 +42,16 @@ public static class Startup
         // within a session and reset on a fresh page load (see WaveformVisualizerControlState).
         services.AddScoped<WaveformVisualizerControlState>();
 
-        // 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. 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).
+        // Phase 16 anonymous telemetry (client side), transport-resilience split. IEventPoster is the
+        // first-party HttpClient POST used for normal play closes (end/switch/stop) and every share — a
+        // same-origin fetch that privacy/tracking heuristics don't name-match. BeaconInterop wraps
+        // sendBeacon and is retained only for the tab-unload edge. The play sink picks the arm; the share
+        // tracker is fetch-only. 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. 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<IEventPoster, HttpEventPoster>();
         services.AddScoped<BeaconInterop>();
         services.AddScoped<IAnonIdProvider, AnonIdProvider>();
         services.AddScoped<IPlayEventSink, BeaconPlayEventSink>();