Add security analysis for RBAC and container security

Create a security analysis module for Kubernetes:

Features to implement

• RBAC permission checking and visualization
• ServiceAccount validation
• Pod security context analysis
• Secret management validation
• Network policy compliance checking
• Container image security scanning (integration with external tools)

Implementation details

• Create lib/analyzers/security.sh module
• Add security analysis to pod troubleshooting
• Create interactive security assessment menu
• Add basic security best practices checker