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/create.rb

@@ -38,8 +38,6 @@ module Sessions
         session.create_score_state!
         mtx = Mediamtx::Client.new
         mtx.create_path(session)
-        mtx.create_overlay_path(session)
-        start_overlay_relay(session)
         log_event(session, "pairing", { created: true, platform: session.platform })
       end
 
@@ -66,12 +64,6 @@ module Sessions
       Youtube::SetupBroadcast.call(session, youtube_channel: youtube_channel)
     end
 
-    def start_overlay_relay(session)
-      Streams::OverlayRelay.start(session)
-    rescue Streams::OverlayRelay::Error => e
-      Rails.logger.warn("[Sessions::Create] Overlay relay: #{e.message}")
-    end
-
     def log_event(session, type, metadata)
       session.stream_events.create!(event_type: type, metadata: metadata, occurred_at: Time.current)
     end