Change forking to read the rollout from file (#3440)

This PR changes get history op to get path. Then, forking will use a
path. This will help us have one unified codepath for resuming/forking
conversations. Will also help in having rollout history in order. It
also fixes a bug where you won't see the UI when resuming after forking.

codex-rs/mcp-server/src/codex_tool_runner.rs

@@ -277,7 +277,7 @@ async fn run_codex_tool_session_inner(
                     | EventMsg::GetHistoryEntryResponse(_)
                     | EventMsg::PlanUpdate(_)
                     | EventMsg::TurnAborted(_)
-                    | EventMsg::ConversationHistory(_)
+                    | EventMsg::ConversationPath(_)
                     | EventMsg::UserMessage(_)
                     | EventMsg::ShutdownComplete => {
                         // For now, we do not do anything extra for these