Stabilizza live YouTube/RTMP e fix crash rotazione mobile.

Pipeline YouTube con relay, overlay e publisher sync lato backend; fix GL pauseGlDuringRotation su Android per evitare crash in rotazione durante lo streaming Flutter.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/services/sessions/pause.rb

@@ -7,11 +7,12 @@ module Sessions
     def call
       cancel_timeout_job
       @session.pause! if @session.may_pause?
-      # Slate già su path (create_path + alwaysAvailable): stop RTMP basta, senza patch API.
+      Mediamtx::Client.new.set_always_available(@session, enabled: true)
+      # Slate su path per HLS in pausa; RTMP telefono si ferma via comando app.
       log_event("paused")
       SessionChannel.broadcast_message(@session, { type: "command", action: "pause_stream" })
       SessionChannel.broadcast_message(@session, { type: "stream_event", event: "paused" })
-      Streams::Overlay::Refresh.call(@session)
+      Youtube::LivePipeline.schedule!(@session, force: true) if @session.platform == "youtube"
       @session
     end