Security: Implement RestrictedPython for safer custom code execution

[coderabbitai]

Background

Currently, the custom code compiler uses raw exec() to execute user-provided Python code, which could potentially be unsafe as it has unrestricted access to Python builtins and the global namespace.

Proposed Solution

Implement RestrictedPython to provide a safer execution environment for custom code. This will:

1. Restrict access to potentially dangerous builtins
2. Run code in an isolated namespace
3. Prevent access to sensitive operations

References

• Original PR discussion: feat(source-declarative-manifest): add support for custom Python components from dynamic text input #174 (comment)

Implementation Notes

• Add RestrictedPython as a dependency
• Replace current exec() implementation with RestrictedPython's secure execution
• Add tests to verify security restrictions are working as expected

Security Considerations

This enhancement will improve the security posture of the custom code execution feature by preventing potentially malicious code from accessing sensitive operations or resources.