docs: rewrite rip-recovery + drive-access for 0.13.6 single-shot model

Updates docs/ to reflect the recovery-loop strip:
- rip-recovery.md: drops Phase 1/2/3 description, replaces with three-layer
  model (Disc::patch multi-pass / DiscStream batch halving / Drive::read
  single-shot). Notes that no SCSI resets fire from any retry path.
- drive-access.md: removes SG_SCSI_RESET + STOP/START UNIT escalation
  references; SgIoTransport::reset is now kernel SG_IO flush + ALLOW
  MEDIUM REMOVAL only.
- src/mux/disc.rs + tests/: cargo fmt cleanup.

tests/integration_progress_and_halt.rs

@@ -199,7 +199,10 @@ fn test_disc_copy_progress_callback_fires() {
     let n = calls.load(Ordering::Relaxed);
     let last = last_bytes.load(Ordering::Relaxed);
     assert!(n > 0, "on_progress should fire at least once, got {n}");
-    assert!(last > 0, "final progress bytes should be non-zero, got {last}");
+    assert!(
+        last > 0,
+        "final progress bytes should be non-zero, got {last}"
+    );
 }
 
 // ── 3. Halt aborts disc copy promptly ─────────────────────────────────────