Implement TestWork functionality for preserving working directories on failure

Co-authored-by: imjasonh <210737+imjasonh@users.noreply.github.com>

README.md

@@ -102,6 +102,7 @@ testscript::run("testdata")
         Ok(())
     })
     .condition("feature-enabled", true)
+    .preserve_work_on_failure(true)  // Debug failed tests
     .execute()
     .unwrap();
 ```
@@ -200,3 +201,32 @@ stdout "my-tool 2.1.0"
 ```
 
 This feature only updates `stdout` and `stderr` expectations while preserving file structure and comments.
+
+## TestWork (Debug Failed Tests)
+
+When tests fail, you can preserve the working directory to inspect the test environment and debug issues:
+
+```rust
+testscript::run("testdata")
+    .preserve_work_on_failure(true)
+    .execute()
+    .unwrap();
+```
+
+When a test fails with this option enabled, you'll see output like:
+
+```
+Test failed. Work directory preserved at: /tmp/testscript-work-abc123
+You can inspect the test environment:
+  cd /tmp/testscript-work-abc123
+  ls -la
+```
+
+This feature matches Go's testscript `TestWork` functionality and makes debugging much easier by allowing you to:
+
+- Inspect files created during test execution
+- Manually run commands that failed
+- Understand the exact state when the test failed
+- Debug complex test scenarios step-by-step
+
+The working directory contains all files from the test script's file blocks, plus any files created during test execution.