Architectural cleanup. autorip + freemkv CLI were reimplementing drive
discovery (sysfs walking, type-5 filtering, sg-path construction) and
calling SCSI reset primitives directly. All of that hardware-aware code
moves into libfreemkv with two cheap public probes:
- DriveInfo + list_drives() — multi-OS enumeration (Linux/macOS/Windows)
with peripheral-type-5 filtering and INQUIRY identity. Cheap.
- drive_has_disc(path) — single TUR with internal wedge recovery
escalation (SCSI reset → USB reset → retry) hidden from callers.
USB-layer reset (USBDEVFS_RESET / IOUSBDeviceInterface::ResetDevice /
storport's combined reset) wired across all three platforms.
Visibility tightening — scsi::reset, scsi::usb_reset, and the timeout
constants are now pub(crate). Compile-time guarantee that no consumer
crate can issue SCSI commands directly.
233 lib tests pass; clippy clean.