- SectorReader trait decouples disc scanning from SCSI
- Disc::scan_image() for ISO and any sector source
- resolve_encryption() handles AACS 1.0/2.0/none in one path
- IsoStream: full UDF/MPLS/CLPI/labels pipeline from ISO files
- StdioStream: stdin/stdout pipe
- Strict scheme:// URL format with validation
- Labels module refactored to SectorReader
- 7 stream types total