docs(cortex-cli): add comprehensive deep code review and analysis (#173)

This commit adds a detailed code review document for the cortex-cli crate covering:

- Security concerns and potential vulnerabilities
- Error handling issues and inconsistencies
- Code quality and maintainability concerns
- Performance analysis
- Missing functionality tracking
- Code duplication identification
- Testing gaps

Key findings include:
- URL validation bypass possibilities in MCP commands
- Incomplete sandbox implementation on non-Linux platforms
- Naming inconsistency between 'Fabric' and 'Cortex'
- Duplicated utility functions across modules
- Several 'not yet implemented' stubs in public API

The review provides prioritized recommendations for improvement.

Co-authored-by: Droid Agent <droid@factory.ai>

Author: echobt