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/jobs/stream_publisher_sync_job.rb

@@ -0,0 +1,37 @@
+# Poll MediaMTX + pipeline YouTube automatica (webhook MediaMTX non disponibile in prod).
+class StreamPublisherSyncJob < ApplicationJob
+  queue_as :default
+
+  INTERVAL = 5.seconds
+  ACTIVE_STATUSES = %w[connecting live reconnecting paused].freeze
+  REDIS_CHAIN_KEY = "stream_publisher_sync:chain"
+  RUN_LOCK_KEY = "stream_publisher_sync:run_lock"
+
+  def self.ensure_chain
+    return if redis.get(REDIS_CHAIN_KEY)
+
+    redis.set(REDIS_CHAIN_KEY, "1", ex: INTERVAL.to_i * 4)
+    set(wait: INTERVAL).perform_later
+  end
+
+  def self.redis
+    @redis ||= Redis.new(url: ENV.fetch("REDIS_URL", "redis://localhost:6379/0"))
+  end
+
+  def perform
+    return unless self.class.redis.set(RUN_LOCK_KEY, "1", nx: true, ex: INTERVAL.to_i)
+
+    begin
+      self.class.redis.set(REDIS_CHAIN_KEY, "1", ex: INTERVAL.to_i * 4)
+
+      StreamSession
+        .where(status: ACTIVE_STATUSES)
+        .find_each do |session|
+          Mediamtx::PublisherSync.new(session).call
+        end
+    ensure
+      self.class.set(wait: INTERVAL).perform_later
+      self.class.redis.del(RUN_LOCK_KEY)
+    end
+  end
+end