fix(guardian): fix ordering of guardian events (#16462)

Guardian events were emitted a bit out of order for CommandExecution
items. This would make it hard for the frontend to render a guardian
auto-review, which has this payload:
```
pub struct ItemGuardianApprovalReviewStartedNotification {
    pub thread_id: String,
    pub turn_id: String,
    pub target_item_id: String,
    pub review: GuardianApprovalReview,
    // FYI this is no longer a json blob
    pub action: Option<JsonValue>,
}
```

There is a `target_item_id` the auto-approval review is referring to,
but the actual item had not been emitted yet.

Before this PR:
- `item/autoApprovalReview/started`
- `item/autoApprovalReview/completed`, and if approved...
- `item/started`
- `item/completed`

After this PR:
- `item/started`
- `item/autoApprovalReview/started`
- `item/autoApprovalReview/completed`
- `item/completed`

This lines up much better with existing patterns (i.e. human review in
`Default mode`, where app-server would send a server request to prompt
for user approval after `item/started`), and makes it easier for clients
to render what guardian is actually reviewing.

We do this following a similar pattern as `FileChange` (aka apply patch)
items, where we create a FileChange item and emit `item/started` if we
see the apply patch approval request, before the actual apply patch call
runs.

codex-rs/app-server/src/thread_state.rs

@@ -16,6 +16,7 @@ use std::sync::Weak;
 use tokio::sync::Mutex;
 use tokio::sync::mpsc;
 use tokio::sync::oneshot;
+use tracing::error;
 
 type PendingInterruptQueue = Vec<(
     ConnectionRequestId,
@@ -116,6 +117,38 @@ impl ThreadState {
     }
 }
 
+pub(crate) async fn resolve_server_request_on_thread_listener(
+    thread_state: &Arc<Mutex<ThreadState>>,
+    request_id: RequestId,
+) {
+    let (completion_tx, completion_rx) = oneshot::channel();
+    let listener_command_tx = {
+        let state = thread_state.lock().await;
+        state.listener_command_tx()
+    };
+    let Some(listener_command_tx) = listener_command_tx else {
+        error!("failed to remove pending client request: thread listener is not running");
+        return;
+    };
+
+    if listener_command_tx
+        .send(ThreadListenerCommand::ResolveServerRequest {
+            request_id,
+            completion_tx,
+        })
+        .is_err()
+    {
+        error!(
+            "failed to remove pending client request: thread listener command channel is closed"
+        );
+        return;
+    }
+
+    if let Err(err) = completion_rx.await {
+        error!("failed to remove pending client request: {err}");
+    }
+}
+
 struct ThreadEntry {
     state: Arc<Mutex<ThreadState>>,
     connection_ids: HashSet<ConnectionId>,