Stop documenting the recovery API that 1.6.0 deleted

Disc::sweep, Disc::patch, Disc::copy, SweepOptions and PatchOptions have
zero occurrences in src/ — recovery moved to freemkv-engine — but they were
still documented in 30 places across README.md, TROUBLESHOOTING.md, six
files under docs/, seven src/ doc comments and a Cargo.toml comment.
README.md is the crate's GitHub front page and carried a full multi-pass
code example that cannot compile.

Two of the src/ references were intra-doc LINKS to deleted items
([`disc::Disc::copy`], [`disc::Disc::patch`] in scsi/mod.rs). They produced
no warning on a normal `cargo doc` only because they sit on pub(crate)
items; `--document-private-items` reports both, and they are gone now.

The README example is deleted rather than rewritten against the engine's
API: libfreemkv documenting a downstream crate's API on its own front page
is the drift that produced this, and it cannot even depend on it. The src/
references become plain code spans naming freemkv_engine::recovery::* —
deliberately not links, for the same reason.

docs/rip-recovery.md was 202 lines about relocated code. It now documents
only what this crate owns — Drive::read, SenseFamily, DiscStream's adaptive
batch halving — plus the read-path design constraints, which belong with the
code that enforces them, and points at freemkv-engine/src/recovery/ for the
strategy. api-design.md's module tree is regenerated from the real src/disc/
and src/drive/ layouts instead of hand-patched; it had listed sweep.rs,
patch.rs, mapfile.rs and read_error.rs, none of which exist.

Three stale facts surfaced while rewriting and are corrected: the read
timeouts are 10 s / 60 s, not the documented 1.5 s / 30 s; Drive::reset and
SgIoTransport::reset no longer exist at all, so "no SCSI reset from any read
path" is now stated as the stronger fact it has become; and verify_title,
listed as a progress-emitting operation, was removed entirely.

CHANGELOG.md keeps its references — those are the historical record of the
releases that shipped the API.

docs/disc-to-rip.md

@@ -79,7 +79,7 @@ Insert disc
      │  Or: read sectors → decrypt → raw bytes (for ISO output)
      │  Drive::read() is single-shot. DiscStream::fill_extents adapts the
      │  batch size on failure (halve / probe-up). Bad-range retry is layer
-     │  1 above this — Disc::patch re-runs against the mapfile.
+     │  1 above this — freemkv_engine::recovery::patch re-runs against the mapfile.
      │
      ▼
   PES frames → output stream (MKV, M2TS, network, etc.)
@@ -123,7 +123,7 @@ output.finish()?;
 | aacs/ | [aacs.md](aacs.md) | Key resolution + content decrypt + bus handshake |
 | css/ | -- | DVD CSS cipher |
 | decrypt.rs | -- | Unified decrypt dispatcher (AACS/CSS/None) |
-| disc/ | [rip-recovery.md](rip-recovery.md) | Disc::scan + Disc::sweep + Disc::patch + mapfile |
+| disc/ | [rip-recovery.md](rip-recovery.md) | Disc::scan (sweep/patch/mapfile moved to freemkv-engine in 1.6.0) |
 | labels/ | -- | BD-J stream labels (5 format parsers) |
 | mux/ | -- | Stream implementations (7 stream types) |
 | pes.rs | -- | PES frame types + FrameSource / FrameSink traits |