docs: Document `Attributes` for `NamedTuple`, dataclass, and `TypedDict` fields

[tony]

autodoc renders every field of a NamedTuple, dataclass, or TypedDict whether or not the docstring describes it. An undocumented NamedTuple field reaches the API docs as "Alias for field number 0"; a dataclass or TypedDict field reaches it bare. AGENTS.md now requires an Attributes section covering every field, and this issue tracks the code that predates that rule.

1 class is missing an Attributes entry for 3 fields in total.

Rendered on the published site today

These modules are named by an autodoc directive under docs/, so the stubs are live in the API docs right now.

• SetupDict (TypedDict) in linkify_issues — missing version, parallel_read_safe, parallel_write_safe

Fixing one

Add a NumPy-style Attributes section naming every field, with its type and what it holds:

class Example(t.NamedTuple):
    """One-line summary.

    Attributes
    ----------
    path : pathlib.Path | None
        What this field holds, and what ``None`` means.
    """

Partial coverage does not help: a class with three fields and two documented still ships a stub for the third.

---

Links are permalinks anchored to v0.0.19; a file that changed since the last release is linked at the current trunk commit instead. Produced by a static AST scan of the package for NamedTuple, dataclass, and TypedDict classes whose docstring omits a field, excluding tests and private classes.