Nested class/struct types were dropped because the field_declaration branch returned
before walking the class_specifier in its type field. Walk it instead, so nested types
and their members are emitted with a contains edge from the enclosing type. C++/CLI
(ref class, gcnew, ^/% handles) cannot be parsed by tree-sitter-cpp at all (it produces
ERROR nodes and fabricates symbols), so normalize those tokens to plain C++ before
parsing, preserving byte length and line breaks; SCREAMING_CASE constants and attached
XOR/modulo operators are kept out of the handle rewrite.
