1.6.0: remove recovery strategy (moved to freemkv-engine) + trim dead surface

The sweep/patch recovery strategy, mapfile, retry-decision state machine,
section-recover, and damage classification move out of libfreemkv into the
new freemkv-engine crate. libfreemkv keeps the raw single-shot read and
SCSI-fact translation (SenseFamily stays in scsi).

- Delete disc/{sweep,patch,mapfile,read_error,section_recover}.rs, the
  Disc::copy/sweep/patch methods, the Copy/Sweep/Patch option+result types,
  classify_damage/DamageSeverity, progress_snapshot_from_mapfile, and the
  three recovery integration tests.
- Trim public surface the recovery deletion orphaned: delete the dead
  READ_PIPELINE_DEPTH const, the write-side SectorSink/FileSectorSink (no
  consumer), and the DriveSpeed enum (its one live use — set max drive
  speed — becomes Drive::SPEED_MAX_KBPS). Make mapfile_path_for,
  decrypt_sectors_mapped pub(crate); gate NoopEvents to test.
- Version 1.6.0.

src/drive/mod.rs

@@ -483,7 +483,7 @@ impl Drive {
         // the stock riplock). A stock-mode drive with no firmware unlocker still
         // wants max speed. Best-effort: a failure here must NOT fail the rip.
         if r.is_ok() {
-            self.set_speed(crate::speed::DriveSpeed::Max.to_kbps());
+            self.set_speed(Self::SPEED_MAX_KBPS);
             // Ask the drive to REPORT recovered/marginal reads rather than
             // silently commit best-effort data as GOOD (the dirty-disc
             // "passed-clean-but-decodes-with-errors" trap). Best-effort: a drive
@@ -951,6 +951,9 @@ impl Drive {
         decode_read_capacity(&buf, result.bytes_transferred)
     }
 
+    /// SET CD SPEED "use the drive's maximum" sentinel (0xFFFF KB/s per MMC).
+    pub const SPEED_MAX_KBPS: u16 = 0xFFFF;
+
     pub fn set_speed(&mut self, speed_kbs: u16) {
         let cdb = crate::scsi::build_set_cd_speed(speed_kbs);
         let mut dummy = [0u8; 0];