docs(tools): add README + comprehensive tests for security tools

[Emart29]

Description

Adds comprehensive documentation and unit tests for all 7 security scanning tools.

Fixes #5094

READMEs Added (7 files)

Tool	Purpose
port_scanner	TCP connect scans, banner grabbing, risky port detection
ssl_tls_scanner	TLS version, cipher suite, certificate analysis
http_headers_scanner	OWASP security headers validation
dns_security_scanner	SPF, DMARC, DKIM, DNSSEC, zone transfer checks
subdomain_enumerator	Passive CT log subdomain discovery
tech_stack_detector	Web technology fingerprinting
risk_scorer	Weighted letter-grade risk scoring

Each README includes:

• Feature description and usage examples
• API reference with parameters and response format
• Security checks explained with severity levels
• Ethical use guidelines
• Error handling
• Integration with risk_scorer

Unit Tests Added (92 total)

Expanded test_security_tools.py with comprehensive coverage:

• Port Scanner: Constants, port categories, async _check_port tests
• SSL/TLS Scanner: Weak ciphers, insecure TLS versions, cert date parsing
• HTTP Headers Scanner: Security headers, leaky headers validation
• DNS Security Scanner: SPF/DMARC/DKIM/DNSSEC policy checks
• Subdomain Enumerator: Keyword detection, severity levels
• Tech Stack Detector: Cookie analysis, CDN/CMS/framework detection
• Risk Scorer: Grading logic, category scoring, JSON parsing, inverted checks

Testing

cd tools
pytest tests/tools/test_security_tools.py -v
# 92 passed in 1.17s

Checklist

• READMEs follow existing tool documentation patterns
• All 92 tests pass locally
• Lint passes (ruff check)
• Ethical use guidelines included for security tools

[bryanadenhq]

Hi @Emart29, thanks for your contribution, please address the review comment

[bryanadenhq]

Changes to this file is unnecessary, just keeping the readme is already good.