Which issue(s) does this change fix?

• Fixes Terraform integration test failures with ModuleNotFoundError: No module named 'samcli'
• Also, add tmp folder generated during integration test run in .gitignore

Why is this change necessary?

During Terraform builds, SAM CLI copies zip.py from samcli/local/lambdafn/ to an isolated temporary directory (.aws-sam-iacs/iacs_metadata/) where it's executed as part of the build process. The original code imported UserException from samcli.commands.exceptions, but the samcli package is not available in this isolated directory, causing the import to fail with ModuleNotFoundError.

How does it address the issue?

This change replaces the custom UserException with Python's built-in ValueError exception in the _extract function within samcli/local/lambdafn/zip.py. This eliminates the dependency on SAM CLI's internal module structure, making zip.py self-contained and able to run successfully when copied to the isolated metadata directory. The error handling behavior remains functionally equivalent.

• File: samcli/hook_packages/terraform/hooks/prepare/makefile_generator.py (lines 96-97)

ZIP_UTILS_MODULE_script_path = os.path.join(samcli_root_path, "local", "lambdafn", ZIP_UTILS_MODULE)
shutil.copy(ZIP_UTILS_MODULE_script_path, output_directory_path)

Mandatory Checklist

PRs will only be reviewed after checklist is complete

• Review the generative AI contribution guidelines
• Add input/output type hints to new functions/methods
• Write design document if needed (Do I need to write a design document?)
• Write/update unit tests
• Write/update integration tests
• Write/update functional tests if needed
• make pr passes
• make update-reproducible-reqs if dependencies were changed
• Write documentation

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.