🧪 Add missing error path test for zip_dir

[Tcode-Motion]

🎯 What: Added a missing error path test for the zip_dir function in stdlib/src/compress.rs. Previously, the function did not have test coverage verifying its behavior when encountering I/O errors, such as when attempting to zip a directory that does not exist.

📊 Coverage: The new test test_zip_dir_error_path ensures that passing a non-existent source directory to zip_dir correctly results in an Err result, covering the expected failure scenario.

✨ Result: Improved test coverage and reliability for standard library I/O functions. This provides a safety net ensuring that future refactoring of zip_dir will maintain expected error handling behavior.

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PR created automatically by Jules for task 12670569601164286779 started by @Tcode-Motion

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