Resume conversation from an earlier point in history (#2607)

Fixing merge conflict of this: #2588


https://github.com/user-attachments/assets/392c7c37-cf8f-4ed6-952e-8215e8c57bc4

codex-rs/tui/src/app_event.rs

@@ -1,3 +1,4 @@
+use codex_core::protocol::ConversationHistoryResponseEvent;
 use codex_core::protocol::Event;
 use codex_file_search::FileMatch;
 use ratatui::text::Line;
@@ -57,4 +58,7 @@ pub(crate) enum AppEvent {
 
     /// Update the current sandbox policy in the running app and widget.
     UpdateSandboxPolicy(SandboxPolicy),
+
+    /// Forwarded conversation history snapshot from the current conversation.
+    ConversationHistory(ConversationHistoryResponseEvent),
 }