feat(contracts): implement credential security audits and audit reporting

[rohan911438]

Summary

This PR introduces credential security auditing and activity tracking capabilities to the Soroban credential contracts.

Added

• Credential operation audit logging
• Audit event definitions
• Suspicious activity tracking
• Credential security validation checks
• Audit report generation
• Contract event emission for credential lifecycle actions

Security Improvements

• Detection of abnormal credential activity
• Tracking of unauthorized access attempts
• Credential verification monitoring
• Revocation access monitoring

Tests

Added coverage for:

• Audit record creation
• Suspicious activity detection
• Security validation failures
• Audit report generation
• Event emission validation

Result

All credential operations are now auditable and traceable while providing a foundation for compliance and security monitoring.

Closes #94

[vercel]

@rohan911438 is attempting to deploy a commit to the Josie's projects Team on Vercel.

A member of the Team first needs to authorize it.

[Josie123-Dev]

Hi @rohan911438,

The CI is currently failing on your PR because the Rust formatting check (cargo fmt -- --check) did not pass.

The changes in auditing.rs, events.rs, lib.rs, and test.rs contain formatting differences that need to be fixed by rustfmt. Please run the following command locally:

cargo fmt

Then commit the formatting changes and push the updated code.

Once the formatting issues are resolved, the CI should pass successfully.

Please update the PR when the fix has been pushed.

Thanks.