feat: Allow customizing the responses, flows in Captain (#11385)

- Ability to provide custom instructions to captain

<img width="1107" alt="Screenshot 2025-04-28 at 6 11 43 PM"
src="https://github.com/user-attachments/assets/f94cbccc-b4d8-48fd-b6b9-55524129bc50"
/>

enterprise/app/policies/captain/assistant_policy.rb

@@ -18,4 +18,8 @@ class Captain::AssistantPolicy < ApplicationPolicy
   def destroy?
     @account_user.administrator?
   end
+
+  def playground?
+    true
+  end
 end