Centralize configuration sources

Maintain configuration settings in a single authoritative source to avoid duplication and inconsistencies across multiple files. When possible, use pyproject.toml as the primary configuration file and remove redundant specifications from other files like .pre-commit-config.yaml and Makefile.

This approach follows the DRY (Don’t Repeat Yourself) principle and ensures that configuration changes only need to be made in one place, reducing maintenance overhead and preventing configuration drift.

Example:

# pyproject.toml - Single source of truth
[tool.ruff.lint]
select = [
    "UP018",
    "UP032", 
    "UP034",
    "W",        # -- Warnings, including invalid escape-sequence --
]
ignore = [
    "COM812",
    "PT005",    # -- flags mock fixtures with names intentionally matching private method name --
    "PT011",
]

Remove redundant ruff configurations from .pre-commit-config.yaml and Makefile so they automatically pick up settings from pyproject.toml.