feat(analytics): implement analytics engine metrics (pageviews, visitors, sources, devices, countries)

[ansabazys]

Summary

This PR implements the core analytics engine for Tracpy by adding aggregation endpoints for website analytics metrics.

Features Implemented

• Page view aggregation
• Unique visitor tracking
• Traffic source analytics
• Device and browser analytics
• Country analytics

Endpoints Added

• GET /analytics/pageviews/:websiteId
• GET /analytics/pages/:websiteId
• GET /analytics/visitors/:websiteId
• GET /analytics/sources/:websiteId
• GET /analytics/devices/:websiteId
• GET /analytics/browsers/:websiteId
• GET /analytics/countries/:websiteId

Implementation Details

• Aggregations are computed from the Event table.
• Raw SQL queries are used for efficient grouping and counting.
• Controllers handle request validation and response formatting.
• Services encapsulate analytics aggregation logic.

Related Issues

Closes:

• Implement Page View Aggregation #31 Implement Page View Aggregation
• Implement Unique Visitor Tracking #32 Implement Unique Visitor Tracking
• Implement Traffic Source Tracking #33 Implement Traffic Source Tracking
• Implement Device and Browser Analytics #34 Implement Device and Browser Analytics
• Implement Country Analytics #35 Implement Country Analytics