Add dev message upon review out

[dedrisian-oai]

Proposal: We want to record a dev message like so:

{
      "type": "message",
      "role": "user",
      "content": [
        {
          "type": "input_text",
          "text": "<user_action>
  <context>User initiated a review task. Here's the full review output from reviewer model. User may select one or more comments to resolve.</context>
  <action>review</action>
  <results>
  {findings_str}
  </results>
</user_tool>"
        }
      ]
    },

Without showing in the chat transcript.

Rough idea, but it fixes issue where the user finishes a review thread, and asks the parent "fix the rest of the review issues" thinking that the parent knows about it.

Question: Why not a tool call?

Because the agent didn't make the call, it was a human. + we haven't implemented sub-agents yet, and we'll need to think about the way we represent these human-led tool calls for the agent.