vsc-core — Windows Volume Shadow Copy (VSS) reader

A panic-free decoder for the on-disk structures of Windows Volume Shadow Copy (VSS), the [P^H] disk-history substrate of the forensic fleet. Given a positioned Read + Seek over an NTFS volume (offset 0 = the NTFS boot sector), [VssVolume::open] reads the VSS volume header at byte offset 0x1E00, walks the catalog of shadow-copy stores, and exposes each store's [StoreInfo] on demand.

The reader stays pure: it decodes bytes into typed records and makes no forensic judgments (those live in the sibling vsc-forensic analyzer). It never loads the whole volume into memory — the real volumes are hundreds of gigabytes — and every multi-byte read is bounds-checked, so malformed input yields safe defaults or a typed [VssError], never a panic.

Phase 1 (this crate) enumerates stores and decodes store information plus the typed diff-area records ([BlockDescriptor], [StoreBlockRange]). The copy-on-write block-reconstruction engine is Phase 2 and out of scope here.