Chore/lint implementation

[emidiovaleretto]

Context

Code formatting issues (whitespace, trailing spaces) were slipping into commits
and only getting caught by flake8 in CI — causing avoidable failed pipelines and
follow-up "style: fix" commits.

What

• Add black (code formatter) and pre-commit to development.txt
• Add .pre-commit-config.yaml running black and flake8 as commit hooks
• Add [tool.black] config in pyproject.toml with line-length 120
• Format the existing codebase with black (separate commit)

Why

With pre-commit installed, black and flake8 run automatically before every
commit. Formatting issues are fixed (or blocked) locally, so they never reach
CI. Black's line-length is aligned to 120 to match the existing flake8 config,
keeping both tools consistent.

How it works

• pre-commit hooks run on git commit: black formats, then flake8 verifies
• Black config lives in pyproject.toml; flake8 reads the existing .flake8
• Developers run pre-commit install once after cloning to activate the hooks

How to verify

Make a formatting error (e.g. trailing whitespace), stage it, and commit —
black fixes it and the commit is blocked until re-staged. Tested locally:
hooks fire correctly, black reformats, flake8 passes.