Add debug timing for thread item pagination (#59497)

## What changed

- Log `thread/items/list` request IDs, cursor kinds, page sizes, next-page availability, elapsed time, and success status.
- Log remote-control item-page response preparation and WebSocket write times, along with request and stream IDs, sequence IDs, frame counts, wire bytes, and success, interruption, or write-error outcomes. Collect these transport metrics only when debug logging is enabled.

GitOrigin-RevId: 0f26bef6d6b8cacbd5a5c76c49a5f882669f6598

codex-rs/app-server/src/request_processors/thread_processor.rs

@@ -1001,11 +1001,29 @@ impl ThreadRequestProcessor {
 
     pub(crate) async fn thread_items_list(
         &self,
+        request_id: &ConnectionRequestId,
         params: ThreadItemsListParams,
     ) -> Result<Option<ClientResponsePayload>, JSONRPCErrorError> {
-        self.thread_items_list_response_inner(params)
-            .await
-            .map(|response| Some(response.into()))
+        let cursor_kind = match &params.cursor {
+            None => "none",
+            Some(ThreadItemsListCursor::Opaque(_)) => "opaque",
+            Some(ThreadItemsListCursor::Anchor(ThreadItemsListAnchor::Item { .. })) => {
+                "item_anchor"
+            }
+        };
+        let started = std::time::Instant::now();
+        let result = self.thread_items_list_response_inner(params).await;
+        let page = result.as_ref().ok();
+        tracing::debug!(
+            request_id = %request_id.request_id,
+            cursor_kind,
+            item_count = page.map(|page| page.data.len()),
+            has_next_page = page.map(|page| page.next_cursor.is_some()),
+            duration_ms = started.elapsed().as_millis() as u64,
+            success = result.is_ok(),
+            "thread/items/list finished"
+        );
+        result.map(|response| Some(response.into()))
     }
 
     pub(crate) async fn thread_items_read(