IA-939 : add activity log, session management, and profile photo endpoint

Summary

This MR introduces three main features to the user management service: activity history tracking, active session management, and a dedicated admin profile photo update endpoint.

Changes

New Features

• Activity Log: Track user actions (password change, 2FA toggle, photo update, profile edit) via UserStatusHistory entries, exposed through GET /users/activity-log
• Session Management: Register, list, and revoke active user sessions with Keycloak integration, exposed through:
  • GET /users/sessions
  • DELETE /users/sessions/{tokenId}
  • DELETE /users/sessions/others
• Admin Profile Photo Endpoint: Dedicated PUT /admins/current-user/photo endpoint to handle photo upload/delete and visibility separately from profile info update

Modified Files

• UserServiceImpl — added activity logging in changePassword and saveTwoFactorPreference
• AdminServiceImpl — added activity logging in updateAdmin and updateCurrentAdmin, added updateCurrentAdminPhoto implementation
• AdminController — added PUT /current-user/photo endpoint
• ApiPaths — added CURRENT_USER_PHOTO, ACTIVITY_LOG, SESSIONS constants

New Files

• HistoryService / HistoryServiceImpl / HistoryController
• UserSessionRepository
• UserStatusHistoryRepository (updated with custom query)
• UserActivityResponse / UserSessionResponse
• UserSession entity