Add black formatting to pre-commit hook with npm install

[Copilot]

Adds black Python formatter to the existing pre-commit hook, auto-installed via npm install.

Changes

• pyproject.toml: Added black>=24.0.0 to dev dependencies with standard configuration (88 line length, py311/py312 targets)

• pre-commit hook:

  • Auto-activates .venv when present
  • Runs black on staged Python files before ruff/mypy
  • Auto-formats and prompts re-stage if needed
  • Fixed Python file detection (git glob patterns → grep)

• Documentation: Updated .githooks/README.md with black workflow and requirements

Behavior

First commit attempt with unformatted code:

$ git commit -m "Add feature"

🔍 Running linting checks on Python files...
  ✓ Running black...

❌ Black formatting check failed! Auto-formatting files...
reformatted tests/example.py

✅ Files have been auto-formatted with black.
   Please stage the formatted files and commit again:
   git add tests/example.py

Re-stage and commit succeeds:

$ git commit -m "Add feature"

🔍 Running linting checks on Python files...
  ✓ Running black...
  ✓ Black formatting check passed
  ✓ Running ruff...
  ✓ Ruff passed
✅ All linting checks passed!

Gracefully degrades if black not installed (warns but allows commit).

Original prompt

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This section details on the original issue you should resolve

<issue_title>add black formatting to git hooks</issue_title>
<issue_description>make sure this hook is also installed by npm install</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes add black formatting to git hooks #114

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