Add STRIDE threat modeling framework

[aravikishan]

Feature Request

Adding STRIDE (Spoofing, Tampering, Repudiation, Information Disclosure, Denial of Service, Elevation of Privilege) as a threat modeling framework would make CyberSim much more useful for security assessments.

Proposed features

• Automatic STRIDE classification for each simulated threat
• Data flow diagram (DFD) generation
• Threat-to-mitigation mapping
• Export to standard formats (JSON, PDF report)

This would complement the existing CVSS scoring nicely.