fix(formatting): read ruff pin from pyproject.toml, not missing requirements-dev.txt

[latent-9]

Is your pull request related to a problem? Please describe.
formatting.sh aborts before it formats anything, for every contributor who runs it. Line 34 checks the required ruff version by grepping requirements-dev.txt:

tool_version_check "ruff" $RUFF_VERSION "$(grep "ruff==" requirements-dev.txt | cut -d'=' -f3)"

But requirements-dev.txt does not exist in the repo — dev dependencies live in pyproject.toml:

[project.optional-dependencies]
dev = [
    "ruff == 0.11.10"
]

Since the script runs under set -eo pipefail, the failed grep makes the required-version substring empty, so tool_version_check sees a mismatch and does exit 1:

Wrong ruff version installed:  is required, not 0.11.10.

Why should this feature be added?
The dev formatting helper is currently unusable. This repoints the version check at the real source of truth (pyproject.toml) and tolerates its spaced ruff == x.y.z pin (the old cut -d= logic assumed the unspaced ruff== form). One-line change.

Examples

• Before: bash formatting.sh → grep: requirements-dev.txt: No such file or directory → Wrong ruff version installed: is required, not 0.11.10. → exit 1.
• After (ruff 0.11.10 installed): version check passes, ruff format / ruff check run.

Additional context
Verified locally under set -eo pipefail: the new extraction yields exactly 0.11.10 from pyproject.toml, matches a correct install, and still flags a wrong one. bash -n clean.