improve: fix pyproject.toml optional-deps key conflict and clean .gitignore

[Coding-Dev-Tools]

Automated improvement by dev-engineer.

• Renamed [project.optional-dependencies] license to license-check to avoid PEP 621 metadata key conflict with [project] license
• Removed stray nul entry from .gitignore (Windows artifact)

[github-actions]

🤖 Automated Code Review

✅ Ruff Lint — No issues

⚠️ Ruff Format — Formatting needed

Would reformat: src/configdrift/cli.py
Would reformat: src/configdrift/diff.py
Would reformat: src/configdrift/loader.py
Would reformat: tests/test_cli.py
Would reformat: tests/test_coverage_gaps.py
Would reformat: tests/test_diff.py
Would reformat: tests/test_loader.py
7 files would be reformatted, 2 files already formatted

✅ Secret Detection — Clean

✅ Large Files — Within limits

📊 Diff Stats — 2 file(s) changed

 .gitignore     | 1 -
 pyproject.toml | 2 +-
 2 files changed, 1 insertion(+), 2 deletions(-)

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Verdict: ⚠️ Warnings — Lint/format issues found. Recommend fixing before merge.

Automated by Coding-Dev-Tools/.github reusable workflow.