- Update GetSystemStats to query active sessions, total accounts, blocked users, and low balance alerts from database
- Update GetHealthStatus to check database connectivity and set ActiveSync status
- Update GetUsageStats to query usage events by IMSI and period with trend calculation comparing to previous period
- Update GetRealTimeUsage to query current session and today's usage from database
- Update ListUsageEvents to query usage events with
- Add ChargingService with database and charging engine client dependencies
- Add GetSystemStats to retrieve active sessions, accounts, blocked users, and uptime metrics
- Add GetHealthStatus to check Redis connection, sync status, and memory usage
- Add GetUsageStats to get subscriber usage statistics with data/voice/SMS volumes, costs, and trends
- Add GetRealTimeUsage to track current session and today's usage metrics
nutcas3