Add security audits and implement best practices

[gboigwe]

Description

Conduct security audits and implement security best practices across smart contracts and frontend.

Security Checklist

Smart Contract Security

• Reentrancy protection
• Integer overflow/underflow checks
• Access control verification
• Asset restriction validation
• Gas optimization for DoS prevention

Frontend Security

• XSS prevention
• CSRF protection
• Secure session storage
• Input validation
• Environment variable protection

Security Tools

# Smart contract analysis
clarinet check

# Frontend security scan
npm audit
npm audit fix

Acceptance Criteria

• Security audit completed
• Vulnerabilities addressed
• Security documentation created
• Pen testing performed (if applicable)
• Third-party audit (future)

Dependencies

• Issue Implement circle-factory contract with Clarity 4 features #2: Factory contract
• Issue Implement circle-treasury contract with restrict-assets? protection #3: Treasury contract
• All frontend issues

Estimated Complexity

High