refactor: Consolidate users analytis endpoints to profile.summary

MR: User Analytics API Cleanup

Summary

This MR removes three unused user analytics endpoints and consolidates the remaining profile summary data into /users/{id}/profile?include=summary by adding the missing average_edits_per_record field.

What Changed

Backend

• Added average_edits_per_record to profile.summary.edits
• Removed the following unused endpoints from app/api/v1/endpoints/users.py:
  • GET /users/{id}/edit-activity
  • GET /users/{id}/edit-metrics
  • GET /users/{id}/activity-summary
• Removed unused imports from users.py
• Removed obsolete schema exports from app/schemas/__init__.py
• Deleted dead schema classes from app/schemas/record_history.py

Why

• The frontend only uses profile.summary.edits.total_edits
• The profile summary already provides the same analytics data as the removed endpoints
• average_edits_per_record was the only missing field
• This reduces dead code and simplifies the API surface

Impact

• No frontend changes required
• No data loss
• One additive field in the profile summary
• Three unused endpoints removed

Verification

• GET /users/{id}/profile?include=summary returns average_edits_per_record
• GET /users/{id}/edit-activity returns 404
• GET /users/{id}/edit-metrics returns 404
• GET /users/{id}/activity-summary returns 404
• No import or schema errors
• Existing profile UI still works