v0.15.0: multipass CopyOptions, auto-detect sweep vs patch, speed control on damage zone entry/exit

- CopyOptions: replace resume/skip_on_error/batch_sectors with single multipass bool
- Disc::copy() auto-detects pass from mapfile state: no mapfile or NonTried → sweep, only NonTrimmed/Unreadable → patch
- Fix bug where mapfile with NonTried regions incorrectly dispatched to patch mode
- SectorReader::set_speed() default method, Drive impl sends SET CD SPEED
- On damage zone entry: set_speed(0x0000) for better error recovery
- On damage zone exit (50 consecutive good): set_speed(0xFFFF) to restore max speed
- Disc::mapfile_for() returns /tmp/<name>.mapfile for null:// output
- patch_internal/sweep_internal as private helpers, CopyResult gains recovered_this_pass

tests/integration_progress_and_halt.rs

@@ -438,7 +438,7 @@ fn test_disc_copy_completes_full_disc_with_failing_reader() {
 
     let opts = CopyOptions {
         decrypt: false,
-        skip_on_error: true,
+        multipass: true,
 
         ..Default::default()
     };
@@ -518,7 +518,7 @@ fn test_disc_copy_halts_promptly_on_failing_reader() {
 
     let opts = CopyOptions {
         decrypt: false,
-        skip_on_error: true,
+        multipass: true,
 
         halt: Some(halt),
         ..Default::default()
@@ -606,7 +606,7 @@ fn test_disc_copy_marks_failed_ecc_blocks_as_nontrimmed() {
 
     let opts = CopyOptions {
         decrypt: false,
-        skip_on_error: true,
+        multipass: true,
 
         ..Default::default()
     };