improve: add requirements.txt, enhance SECURITY.md, update CONTRIBUTING.md

[Coding-Dev-Tools]

Automated improvement by dev-engineer

Changes

• Add requirements.txt for pip install -r requirements.txt compatibility
• Enhance SECURITY.md with supported versions table, security architecture, threat model, and compliance info
• Update CONTRIBUTING.md with better formatting, testing guidance, security section, and conventional commits

Verification

• All 69 tests pass
• Ruff lint passes
• CI workflow updated with requirements.txt install

[github-actions]

🤖 Automated Code Review

✅ Ruff Lint — No issues

⚠️ Ruff Format — Formatting needed

Would reformat: src/apiauth/cli.py
Would reformat: src/apiauth/keygen.py
Would reformat: tests/conftest.py
Would reformat: tests/test_cli.py
4 files would be reformatted, 4 files already formatted

🔴 Secret Detection — 2 potential secret(s)

  .ruff_cache/CACHEDIR.TAG:1 — Hex High Entropy String
  tests/test_cli.py:419 — Secret Keyword

✅ Large Files — Within limits

📊 Diff Stats — 4 file(s) changed

 .github/workflows/ci.yml | 54 ++++++++++++++++++++++++++++++++++++++++++++++++
 CONTRIBUTING.md          | 26 +++++++++++++++++------
 SECURITY.md              | 32 ++++++++++++++++++++++++++++
 requirements.txt         |  5 +++++
 4 files changed, 111 insertions(+), 6 deletions(-)

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Verdict: 🔴 Changes Requested — Potential secrets detected. Do not merge.

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