Implement Permission Management for Enhanced Security

Shellz currently allows seamless access to multiple shells, which may pose potential security risks in environments with multiple users or sensitive commands. Adding a permission management system will help control access, ensuring secure operation and improved accountability.

## Proposed Enhancements:

- Introduce user roles with varying levels of access (e.g., administrator, read-only, restricted access).
- Allow administrators to define and manage access rules for different shell connections and commands.
- Add a secure authentication mechanism to verify user identities before granting shell access.
- Implement session timeouts and restrictions based on user roles for enhanced security.

## Benefits:

- Improved security for environments handling sensitive data or commands.
- Better control over user access to shell sessions.
- Increased accountability through defined access levels.