improve: remove dangling npm boilerplate from README

[Coding-Dev-Tools]

Automated improvement by dev-engineer.

[github-actions]

🤖 Automated Code Review

✅ Ruff Lint — No issues

⚠️ Ruff Format — Formatting needed

Would reformat: src/json2sql/cli.py
Would reformat: src/json2sql/converter.py
Would reformat: tests/test_cli.py
Would reformat: tests/test_remaining_coverage.py
4 files would be reformatted, 7 files already formatted

✅ Secret Detection — Clean

✅ Large Files — Within limits

📊 Diff Stats — 1 file(s) changed

 README.md | 12 ------------
 1 file changed, 12 deletions(-)

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

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