- Created AnalyticsAggregationService for analytics_events table
- Aggregation by event type and time period (hour, day, week, month)
- Support for filtering by event names and user ID
- Features: event counts, unique users, average per user, payload summary
- Top events ranking and user activity counts
- Uses PostgreSQL date_trunc and to_char for period grouping
- Added unit tests for service validation and helper functions
