v0.7.1: SectorReader trait, IsoStream, StdioStream, resolve_encryption

- 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

src/sector.rs

@@ -0,0 +1,14 @@
+//! SectorReader — trait for reading 2048-byte disc sectors.
+//!
+//! Implemented by DriveSession (SCSI) and IsoFile (file-backed).
+//! Used by UDF parser, disc scanner, label parsers — anything that
+//! reads sectors doesn't need to know where they come from.
+
+use crate::error::Result;
+
+/// Read 2048-byte sectors from a disc or disc image.
+pub trait SectorReader {
+    /// Read `count` sectors starting at `lba` into `buf`.
+    /// `buf` must be at least `count * 2048` bytes.
+    fn read_sectors(&mut self, lba: u32, count: u16, buf: &mut [u8]) -> Result<usize>;
+}