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/youtube/setup_broadcast.rb

@@ -36,7 +36,7 @@ module Youtube
       @session.reload
       return @session if @session.terminal?
       return @session if @session.platform != "youtube"
-      return @session if @session.youtube_broadcast_id.present?
+      return @session if @session.youtube_broadcast_id.present? && @session.stream_key.present?
 
       yt = BroadcastService.new(@session.match.team, youtube_channel: @youtube_channel)
       title = "#{@session.match.team.name} vs #{@session.match.opponent_name}"
@@ -53,10 +53,7 @@ module Youtube
         rtmp_url: broadcast[:rtmp_url]
       )
 
-      # Relay solo quando _air pubblica (overlay pronto); altrimenti ffmpeg esce subito.
-      if Streams::OverlayRelay.running?(@session.id)
-        Streams::YoutubeRelay.start(@session)
-      end
+      # Relay copy MediaMTX → YouTube parte subito (copertina slate se il telefono non c'è ancora).
       @session.stream_events.create!(
         event_type: "youtube_ready",
         metadata: { broadcast_id: broadcast[:broadcast_id] },
@@ -71,6 +68,7 @@ module Youtube
           youtube_broadcast_id: @session.youtube_broadcast_id
         }
       )
+      Youtube::LivePipeline.schedule!(@session, force: true)
       @session
     rescue BroadcastService::Error => e
       @session.stream_events.create!(