v0.13.20 — sync blocking SG_IO + cross-platform parity strip

- scsi/linux.rs: full rewrite from async write/poll/read+1.5s timeout+
  close-on-timeout to one synchronous ioctl(fd, SG_IO, &hdr). Kernel
  honors hdr.timeout and runs its own ABORT/RESET escalation. Errors
  check host_status and driver_status (both 0xFF-synthesised) plus
  status. Sense-key parser handles descriptor (0x72/0x73) + fixed
  (0x70/0x71) formats. Deleted fd_recovery, bg close+open thread, fd
  swap dance. -331/+155 lines.

- scsi/macos.rs: try_recover() removed (userspace handle-recovery on
  task failure was the same anti-pattern stripped from Linux). bsd_name
  field deleted. Errors bubble up directly.

- scsi/windows.rs: try_recover() removed, wide_path field deleted,
  INVALID_HANDLE guard removed.

- scsi/mod.rs: parse_sense_key() helper extracted (used by all three
  platforms now — single canonical sense-key parse rather than three
  inlined copies). +10 unit tests covering descriptor format, fixed
  format, truncated buffers, unknown response codes.

- drive/mod.rs: Drive::reset() deleted (escalating eject + STOP/START +
  reinit recovery — per audit, kernel handles its own escalation;
  userspace shouldn't).
  pub fn find_drives() -> Vec<Drive> deleted (opened N drives just to
  throw most away). find_drive() now uses discover_drives() directly.
  wait_ready() simplified — drops the reset path on sense_key=5,
  just keeps polling TUR for 60 iterations.

- lib.rs: find_drives re-export removed.

- benches/sgio_read.rs: switched to find_drive() (no longer iterates a
  drive list).

Net: 9 files changed, 226 insertions(+), 473 deletions(-). 329 tests
pass, clippy -D warnings clean. No consumer breakage (CLI, autorip,
bdemu compile + test green).

Architecture decision documented in
(internal)/docs/audits/2026-04-26-scsi-architecture-research.md
(primary-source survey of MakeMKV, sg_dd, ddrescue, and the kernel
mid-layer's own scsi_eh.rst escalation ladder).

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "libfreemkv"
-version = "0.13.18"
+version = "0.13.20"
 edition = "2024"
 rust-version = "1.86"
 license = "AGPL-3.0-only"