Add YARA rule support for custom pattern matching

[NeuZhou]

Feature Request

Support YARA rules as an additional pattern matching engine alongside the existing regex-based rules.

Why

YARA is the industry standard for malware pattern matching. Supporting it would allow security researchers to bring their existing rules and integrate with threat intelligence feeds.

Proposed Implementation

• Parse .yar files from a configurable directory
• Map YARA matches to ClawGuard severity levels
• Support YARA metadata tags for categorization

References

• YARA Documentation
• OWASP Agentic AI Top 10