Fix Process.spawn: redirect log ffmpeg fuori dallo splat

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

backend/app/services/streams/youtube_relay.rb

@@ -21,7 +21,8 @@ module Streams
 
         # YouTube richiede FLV H.264/AAC stabili; -c copy lascia spesso streamStatus=inactive.
         pid = Process.spawn(
-          *youtube_ffmpeg_args(intake, output, log_path),
+          *youtube_ffmpeg_args(intake, output),
+          %i[out err] => log_path,
           pgroup: true
         )
         Process.detach(pid)
@@ -70,7 +71,7 @@ module Streams
 
       # Non usare ffprobe su RTMP live: si blocca e impedisce l'avvio del relay (Sidekiq in hang).
       # Audio: traccia AAC da anullsrc (YouTube la richiede); il mic del telefono resta su _air/HLS.
-      def youtube_ffmpeg_args(intake, output, log_path)
+      def youtube_ffmpeg_args(intake, output)
         [
           "ffmpeg", "-nostdin", "-hide_banner", "-loglevel", "warning",
           "-fflags", "+genpts+discardcorrupt", "-use_wallclock_as_timestamps", "1",
@@ -82,8 +83,7 @@ module Streams
           "-pix_fmt", "yuv420p", "-r", "30", "-g", "30", "-keyint_min", "30", "-sc_threshold", "0",
           "-b:v", "4000k", "-maxrate", "4000k", "-bufsize", "8000k",
           "-c:a", "aac", "-b:a", "128k", "-ar", "48000", "-ac", "1",
-          "-f", "flv", output,
-          %i[out err] => log_path
+          "-f", "flv", output
         ]
       end