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Refactoring Catalog 3: Introduce Parameter Object, Preserve Whole Object, Combine Functions into Class/Transform, Split Phase, Extract/Inline Class and Hide Delegate

Refactorings that group responsibilities gather data that travels together into a type, functions that work together into a class and interleaved phases into separate classes. The post splits Bookstore's CSV import into parse and validate phases with Split Phase, showing with real output a transform turning inconsistent with with, and a Substitute Algorithm equivalence test revealing that the old parser read an English-formatted thousand as 1.2345 TL.