refactor-codebase-with-types

@dmmulroy

Finds refactoring opportunities that replace validation, partial functions, unsafe casts, primitive obsession, and scattered invariants with parsing, precise domain types, and correct-by-construction data. Use when the user wants to refactor a codebase using type-driven design, make illegal states unrepresentable, parse inputs at boundaries, remove redundant checks, or improve static guarantees.