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/Services/StreamingAudioPlayerService.cs

@@ -121,7 +121,7 @@ public class StreamingAudioPlayerService : AudioPlayerService, IStreamingPlayerS
     /// freezes. <see cref="PlayTracker.Close"/> is idempotent, so a later organic close is a no-op.
     /// </summary>
     [JSInvokable]
-    public void OnPageUnload() => _playTracker?.Close();
+    public void OnPageUnload() => _playTracker?.Close(viaUnload: true);
 
     // Advance the play-session high-water mark on each progress tick (§2.1). Seeking backward never
     // lowers it — the tracker takes the max.