Temporarily restrict admin editing with warning notification

[karthik768990]

Summary

This PR temporarily disables editing of existing admin accounts on the Admin Page to prevent potential issues while a larger bug is being fixed.

Changes

• Disabled all input fields and the "Edit Admin" button when editing an existing admin.
• Added a notification suggesting users try incognito mode while the issue is being resolved.
• Maintains full functionality for adding new admin accounts.
• Simplified and cleaned up the template for readability and maintainability.

How to Test

1. Navigate to the Admin Page.
2. Click the edit icon for an existing admin.
3. Verify that inputs and the Edit button are disabled.
4. Confirm that a warning notification appears advising incognito mode.
5. Ensure adding a new admin still works as expected.

Motivation

This is a temporary UX fix to prevent unintended edits while the root cause of the editing issue is being addressed. It improves user guidance and avoids errors in the admin management interface.