🧪 Add test file for scripts/utils.js

[akutuva21]

🎯 What: The testing gap for scripts/utils.js specifically listModelFiles was addressed.
📊 Coverage: Test coverage was added for scenarios such as returning only .bngl files, correctly ordering them alphabetically, ignoring directories (even if named with .bngl), ignoring non-.bngl extensions, and properly handling empty directories. The tests utilize temporary folders ensuring isolation and automatic cleanup without modifying the real codebase layout.
✨ Result: The scripts/utils.js utility functions are now thoroughly tested, improving test coverage and safety for future refactoring efforts without flakiness.

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PR created automatically by Jules for task 12817230383589720297 started by @akutuva21

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