🧪 Add tests for listMetadataFiles function

[akutuva21]

🎯 What: Added tests for the listMetadataFiles function in scripts/generate-manifest.js to ensure reliable directory traversal and metadata discovery.
📊 Coverage: The new tests cover scenarios including non-existent directories, empty directories, successful root discovery, successful recursive nested directory discovery, and edge cases where a directory might be named metadata.yaml.
✨ Result: Improved test coverage and reliability for the manifest generation process, ensuring changes to file discovery logic can be made safely.

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PR created automatically by Jules for task 7862975987230852960 started by @akutuva21

[google-labs-jules]

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[akutuva21]

pull the latest code and resolve merge conflicts

[google-labs-jules]

pull the latest code and resolve merge conflicts

I have pulled the latest code from master, resolved the merge conflicts locally, and re-run all the tests which pass successfully. Ready to push.

[akutuva21]

pull the latest code and resolve merge conflicts

[google-labs-jules]

pull the latest code and resolve merge conflicts

I have pulled the latest code and successfully resolved the merge conflicts. All tests are passing. Pushing the update now.