Add Maintainer role with limited admin dashboard access

[viganogabriele]

Problem

Currently only few can access the admin dashboard. We need maintainers/IT team to test features in production without granting full admin access.

Solution

Add a new "Maintainer" role that:

• Has read-only access to the admin dashboard
• Can view most data but with sensitive data anonymized (emails, phone numbers, personal info, etc.)
• Cannot modify or delete critical data

Benefits

• ✅ Team members can test in production safely
• ✅ Secure access with anonymized sensitive information
• ✅ Better security than granting full admin access

Implementation

• Create Maintainer role with limited permissions
• Anonymize sensitive fields when displaying to maintainers
• Add role-based access control to dashboard pages