[Aschenbath]

With detailed validation, failures inside classes and iterables carry AttributeValidationNote/IterableValidationNotes, so transform_error can hand the target type to format_exception. A failure structuring a standalone value — the common case being a primitive like int at the top level — carried nothing, so the formatter received None and produced a bare "invalid value" with no type.

• New cattrs.ValueValidationNote, attached by BaseConverter.structure when detailed validation is on and a failure escapes without a more specific note and is not a grouped validation error.
• transform_error now reads that note in its standalone branch and passes the type to the formatter: converter.structure("x", int) now yields "invalid value for type, expected int @ $" (was "invalid value @ $"). Nested cases are unchanged.
• format_exception's "expected an iterable" special case for TypeErrors now applies whenever the message matches, not only when no type is known. Previously a List[int] field given a non-iterable said "expected List" while the top-level equivalent said "expected an iterable"; the two now agree.

Tests: three new tests in tests/test_v.py (default formatter output for int/float, a custom formatter receiving the type, and no note without detailed validation). The full test suite passes on this machine (1050 tests across tests/ and tests/strategies/); the only exceptions are three version-gated modules (test_frozendicts_315.py, test_sentinels_315.py, test_gen_dict_649.py) that fail to import on Python 3.12 on unmodified upstream as well.

Fixes #401

[Aschenbath]

Closing this as a duplicate — #832, opened a little earlier, implements the same change (passing the target type to format_exception for standalone values). Apologies for the noise.