Implement role-based team management system

[viganogabriele]

The dashboard needs a comprehensive role system for team management. Currently, there is no granular permission structure.

Proposed features:

1. Capo Admin (Chief Admin) role: A top-level admin with full access to all teams and settings
2. Group Creator role: Users who can create groups but have limited admin privileges
3. Team-specific roles: Define roles that can manage specific teams independently
4. Review and refine existing role permissions across all features
5. Ensure proper permission inheritance and hierarchy

Label: enhancement