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/mux/driver.rs

@@ -223,9 +223,11 @@ pub trait MuxEvents: Send + Sync + 'static {
     fn on_read_error(&self, _lba: u32) {}
 }
 
-/// A [`MuxEvents`] that ignores everything — for callers that render no
-/// progress.
-pub struct NoopEvents;
+/// A [`MuxEvents`] that ignores everything — test-only (production callers
+/// supply their own events sink).
+#[cfg(test)]
+pub(crate) struct NoopEvents;
+#[cfg(test)]
 impl MuxEvents for NoopEvents {}
 
 /// The result of a [`mux_stream`] run.

src/mux/mod.rs

@@ -116,7 +116,7 @@ pub(crate) mod videomap;
 // direct `super::demux_sink::` / `super::fvi_sink::` paths — no re-export needed,
 // and no consumer names these types, so they are not public API.
 pub use disc::DiscStream;
-pub use driver::{MuxEvents, MuxInput, MuxOptions, MuxOutcome, NoopEvents, mux_stream};
+pub use driver::{MuxEvents, MuxInput, MuxOptions, MuxOutcome, mux_stream};
 pub use m2ts::M2tsStream;
 pub use mkvstream::MkvStream;
 pub use mp4::{Mp4FitReport, Mp4SkipReason, fit_report as mp4_fit_report};