Add User Connection Insights via API

Expose detailed connection and bandwidth statistics through the API, including:
- Real-time bandwidth usage for each active connection
- Historical bandwidth usage by:
- Custom date ranges (start/end date)
- Presets such as daily, weekly, monthly, yearly

Optional fields might include:
- Per-device breakdown
- Upload/download split
- Total data transferred

This data would be valuable for usage tracking, reporting, billing, and monitoring. Since most of this information is already available, exposing it via API would be a natural extension and help us provide transparent usage insights to end users.