🧹 [Code health improvement] Extract tmp_path_for and atomic_write

[edithatogo]

🎯 What: The code health issue addressed is code duplication around the tmp_path_for function and the atomic write pattern (save_atomic / write_parquet_atomic) in src/catalog.rs, src/quality.rs and src/pipeline.rs.
💡 Why: How this improves maintainability is by extracting these common patterns into a new src/utils.rs module, which removes redundant code and ensures consistency across modules whenever an atomic write is performed.
✅ Verification: Ran cargo test completely successfully, and also ran rustfmt on the modified files to ensure styling remains intact.
✨ Result: The code is cleaner, and any future modules that require safe atomic file writing can now reuse utils::atomic_write without re-implementing the same tmp file fallback and copy/rename logic.

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PR created automatically by Jules for task 3016069770342254630 started by @edithatogo

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