- Add content_dir field to ASRInput schema
- Pass content_dir from pipeline when creating ASRInput
- Modify _try_official_subtitle to use content_dir for output
- Modify _run_whisper_basic to use content_dir for output
- Add validation for empty video_path in Whisper fallback
Root cause: DownloadProcessor sets content_file="" for video types,
causing Path("").parent to resolve to current directory instead of
content directory. Subtitle files were written to wrong location.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Root cause: BilibiliExtractor sync wrappers use asyncio.run() internally,
which fails when called from async context in BilibiliAdapter.
Fix: Call async methods directly instead of sync wrappers.
Verified: Human confirmed fix works (bilibili_BV16cNMzpExh)