feat: Add new APIs for live reports with team filter (#10994)

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.

app/controllers/api/v2/accounts/live_reports_controller.rb

@@ -0,0 +1,64 @@
+class Api::V2::Accounts::LiveReportsController < Api::V1::Accounts::BaseController
+  before_action :load_conversations, only: [:conversation_metrics, :grouped_conversation_metrics]
+  before_action :set_group_scope, only: [:grouped_conversation_metrics]
+
+  before_action :check_authorization
+
+  def conversation_metrics
+    render json: {
+      open: @conversations.open.count,
+      unattended: @conversations.open.unattended.count,
+      unassigned: @conversations.open.unassigned.count,
+      pending: @conversations.pending.count
+    }
+  end
+
+  def grouped_conversation_metrics
+    count_by_group = @conversations.open.group(@group_scope).count
+    unattended_by_group = @conversations.open.unattended.group(@group_scope).count
+    unassigned_by_group = @conversations.open.unassigned.group(@group_scope).count
+
+    group_metrics = count_by_group.map do |group_id, count|
+      metric = {
+        open: count,
+        unattended: unattended_by_group[group_id] || 0,
+        unassigned: unassigned_by_group[group_id] || 0
+      }
+      metric[@group_scope] = group_id
+      metric
+    end
+
+    render json: group_metrics
+  end
+
+  private
+
+  def check_authorization
+    authorize :report, :view?
+  end
+
+  def set_group_scope
+    render json: { error: 'invalid group_by' }, status: :unprocessable_entity and return unless %w[
+      team_id
+      assignee_id
+    ].include?(permitted_params[:group_by])
+
+    @group_scope = permitted_params[:group_by]
+  end
+
+  def team
+    return unless permitted_params[:team_id]
+
+    @team ||= Current.account.teams.find(permitted_params[:team_id])
+  end
+
+  def load_conversations
+    scope = Current.account.conversations
+    scope = scope.where(team_id: team.id) if team.present?
+    @conversations = scope
+  end
+
+  def permitted_params
+    params.permit(:team_id, :group_by)
+  end
+end