feat(v4): Add API to fetch aggregate reports for inboxes (#10604)

The Inbox Overview section is being updated to offer a more detailed
report, showing an overall view of the account grouped by inboxes. To
view detailed reports and access specific graphs for individual inboxes,
click on the inbox name to navigate to its dedicated report page.

---------

Co-authored-by: Sojan Jose <sojan@pepalo.com>

config/routes.rb

@@ -328,6 +328,7 @@ Rails.application.routes.draw do
             collection do
               get :agent
               get :team
+              get :inbox
             end
           end
           resources :reports, only: [:index] do