fix(worker): conform — use aformat for channel layout (ffmpeg 8 dropped aresample ocl)

ffmpeg 8.x removed the `ocl` shortcut option from aresample (it was a
deprecated alias for out_chlayout). The per-segment trim+normalise call
errored immediately:
  [fc#-1] Error applying option 'ocl' to filter 'aresample': Option not found

Split the chain: aresample handles the sample rate, aformat asserts +
auto-converts to stereo + fltp.

  aresample=48000,aformat=channel_layouts=stereo:sample_fmts=fltp

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

services/worker/src/workers/conform.js

@@ -238,7 +238,10 @@ export const conformWorker = async (job) => {
                `scale=1920:1080:force_original_aspect_ratio=decrease,` +
                `pad=1920:1080:(ow-iw)/2:(oh-ih)/2,` +
                `setsar=1,format=yuv420p`,
-        '-af', 'aresample=48000:ocl=stereo',
+        // ffmpeg 8.x dropped the `ocl=` shortcut on aresample. Use aformat
+        // for the channel layout assertion + auto-conversion; aresample
+        // just sets the rate.
+        '-af', 'aresample=48000,aformat=channel_layouts=stereo:sample_fmts=fltp',
         '-c:v', 'libx264', '-preset', 'ultrafast', '-crf', '18',
         '-pix_fmt', 'yuv420p',
         '-c:a', 'aac', '-b:a', '320k', '-ar', '48000',