Risolve timeout creazione sessione YouTube lato app.

La setup broadcast YouTube (~23s) passa in background job; l'API risponde
subito. Aumentato anche il timeout Dio mobile per createSession YouTube.

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

backend/app/jobs/youtube_broadcast_setup_job.rb

@@ -0,0 +1,12 @@
+class YoutubeBroadcastSetupJob < ApplicationJob
+  queue_as :default
+
+  retry_on Youtube::SetupBroadcast::Error, wait: 10.seconds, attempts: 3
+
+  def perform(session_id, youtube_channel = nil)
+    session = StreamSession.find_by(id: session_id)
+    return unless session
+
+    Youtube::SetupBroadcast.call(session, youtube_channel: youtube_channel.presence)
+  end
+end