Duplicate member email addresses are accepted

[KaremFtayyeh]

Title: Duplicate member email addresses are accepted
Description:
Two different member accounts can be registered with the same email address, which breaks uniqueness and communication.
Steps to Reproduce:

1. Add Member A with email a@b.com.
2. Add Member B also with email a@b.com.
3. Save both members.
   Expected Result:
   System rejects the second member and shows “Email already in use”.
   Actual Result:
   Both members are saved successfully with the same email.
   Severity: Medium
   Priority: P2
   Status: New
   Environment: Chrome 129, Windows 11
   Screenshot / Evidence: