feat: Add the ability for a super admin to define account limits (#3946)

Fixes: #3773

app/controllers/api/v1/accounts/inboxes_controller.rb

@@ -2,6 +2,7 @@ class Api::V1::Accounts::InboxesController < Api::V1::Accounts::BaseController
   include Api::V1::InboxesHelper
   before_action :fetch_inbox, except: [:index, :create]
   before_action :fetch_agent_bot, only: [:set_agent_bot]
+  before_action :validate_limit, only: [:create]
   # we are already handling the authorization in fetch inbox
   before_action :check_authorization, except: [:show]
 
@@ -143,4 +144,10 @@ class Api::V1::Accounts::InboxesController < Api::V1::Accounts::BaseController
       []
     end
   end
+
+  def validate_limit
+    return unless Current.account.inboxes.count >= Current.account.usage_limits[:inboxes]
+
+    render_payment_required('Account limit exceeded. Upgrade to a higher plan')
+  end
 end