Previously only the main sidecar binary got chmod 755. Now all files
in the extraction directory get execute permissions — covers ffmpeg,
ffprobe, and any other bundled binaries. Applied in three places:
- sidecar/mod.rs: after local extraction
- commands/sidecar.rs: after download extraction
- commands/media.rs: removed single-file fix (now handled globally)
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>