Refactoring Summary: Changes since test-passing milestone commit 9fb763300058926db240b94179772753f642cd2a

1. Compound Type Name Reversal
   - All compound type names reversed from suffix-first (e.g. integer_arrayref)
     to prefix-first underscore naming (e.g. arrayref_integer).

2. Typemap Updates
   - lib/typemap.perl entries adjusted to reference new prefix-first type names.

3. C++ SubTypes Refactoring
   - Refactored 1D, 2D, and 3D Array and Hash SubTypes modules in C++:
     * Updated typedefs for prefix-first underscore names.
     * Renamed CHECK, CHECKTRACE, XS_unpack, XS_pack, and to_string routines accordingly.

4. Perl Wrapper Module Updates
   - Updated Perl packages under lib/Perl/Structure to export and wrap new
     prefix-first underscore names for type-checking, stringification,
     and typetest functions in SubTypes*.pm files.

5. Test Suite Adjustments
   - Core t/*.t scripts and all t/lib/Perl/Types/Test/** files updated to use
     the new prefix-first underscore type names across scalar, array,
     hash, and nested compound type tests.

6. Iterative Nested Type Passes (P36–P39)
   - Refined multi-dimensional nested types (e.g. arrayref_arrayref_integer,
     hashref_hashref_arrayref_string) through successive commits,
     ensuring consistent reversal of all combinations.

7. Final Polishing (P40–P42)
   - Cleaned up remaining suffix-first names in GSLMatrix, GMPInteger,
     and various SubTypes modules for complete consistency.

Note: C++ namespace integration and scope-resolution operator changes
will be introduced in later stages and are not covered here.