Cleanup: Docstring formatting

Fix class/method docstrings to fit NumPy style guidelines. Examples here: https://www.sphinx-doc.org/en/master/usage/extensions/example_numpy.html

```python
def f(x: int, y: str) -> bool:
"""
Method summary on one line.

Longer description after a blank line if necessary.
It can be multiple lines.

Parameters
----------
x : int
First parameter.
y : str
second parameter.

Returns
-------
bool
Result of the method.
"""
...
```

No files or tests are named in the issue. Start by locating the Python class and method docstrings in the repository, then compare them with the linked NumPy-style example; done means the applicable docstrings follow that format consistently.

Written by the indexing model from the issue text.