This PR is part of the larger #10849 implementation and introduces a new
Live Reports API to provide real-time conversation metrics.
The /live_reports/conversation_metrics endpoint returns account-level or
team-level conversation statistics, including open, pending, unattended,
and unassigned conversation counts.
The /live_reports/grouped_conversation_metrics endpoint accepts a group
parameter, either team_id or assignee_id, and returns open and
unattended conversation counts based on the specified grouping.
