refactor: optimize agent bot assignment dropdown (#14866)

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

@@ -2,6 +2,8 @@ class Api::V1::Accounts::AssignableAgentsController < Api::V1::Accounts::BaseCon
   before_action :fetch_inboxes
 
   def index
+    # TODO: Remove this opt-in once mobile clients support AgentBot assignees in this payload.
+    @include_agent_bots = params[:include_agent_bots].present?
     agent_ids = @inboxes.map do |inbox|
       authorize inbox, :show?
       member_ids = inbox.members.pluck(:user_id)
@@ -10,6 +12,7 @@ class Api::V1::Accounts::AssignableAgentsController < Api::V1::Accounts::BaseCon
     agent_ids = agent_ids.inject(:&)
     agents = Current.account.users.where(id: agent_ids)
     @assignable_agents = (agents + Current.account.administrators).uniq
+    @agent_bots = @include_agent_bots ? AgentBot.accessible_to(Current.account) : []
   end
 
   private