Feature Request for User/Group Storage Quota Management

What is the problem that this feature would fix?
Cerberus FTP currently does not provide a storage quota (capacity limit) feature for individual users or groups. 
This means users can upload files without restrictions until the disk is full, making it difficult to manage storage resources among different users or departments.

Why is it a problem?
Without quotas, several issues may arise:
- Individual users or departments may occupy large amounts of storage, impacting others.
- Administrators cannot easily track who is using how much space, leading to management confusion.
- When the disk is full, all users are affected, which could disrupt important operations.
- There is no way to allocate storage fairly based on different users’ or groups’ needs.

Is there a workaround you currently have for this problem?
Currently, only external solutions such as manual monitoring, third-party scripts, or system-level disk quotas are possible. However, these:
- Cannot prevent users from exceeding their limits in real time.
- Are not reflected or managed directly within the Cerberus FTP interface.
- Are difficult to maintain and track, increasing the admin’s workload.

Do you have a suggestion on how you would like to see the problem fixed?
I suggest adding a storage quota option in the user or group settings of Cerberus FTP, allowing admins to:
- Set a maximum quota (e.g., 2GB, 10GB) for each user or group.
- Automatically deny uploads when the quota is reached, with a clear error message.
- Display usage and remaining space for each user/group in the admin interface.
- Support warning notifications when usage reaches a set threshold (e.g., 80%).

How big is the problem? Who is affected by this problem (End Users, Admins, etc.)?
This is a medium to high severity issue that affects:
Admins: More time is spent on manual management and handling emergencies due to full disks.
End Users: They may be unable to upload or download files if someone uses up all the space.
Organizations: Risk of operational disruption and important data not being saved due to poor resource allocation.