[rr-]

Add read-only lookups by name next to the lists they mirror, as asked in #89: Docstring.params_by_name, attrs_by_name and raises_by_type.

• Each is a Mapping[str, ...] property: a types.MappingProxyType over a dict built from meta on every access. Nothing is cached, so a lookup always matches meta, and both the type checker and the runtime reject writes to it.
• A name given twice maps to its first item, the same way returns takes the first return. The lists keep every item. For raises this means two conditions that raise ValueError give the first one; raises still has both. Raises with no type are left out.
• raises_by_type covers what raises lists, so warns are in it too.
• No methods_by_name: a method's name is its signature as written, such as run(x, y=1), so a lookup by it would rarely be useful.
• Tests in test_kinds.py cover each style, a repeated name, raises with and without a type, and that a lookup is read-only and follows changes to meta.
• Parity against main: none of 29184 docstrings differ. Bench: worst ratio 1.02 on Python 3.8 and on 3.14.

Closes #89.