Fix TUI compaction item replay (#17657)

Problem: PR #17601 updated context-compaction replay to call a new
ChatWidget handler, but the handler was never implemented, breaking
codex-tui compilation on main.

Solution: Render context-compaction replay through the existing
info-message path, preserving the intended `Context compacted` UI marker
without adding a one-off handler.

codex-rs/tui/src/chatwidget.rs

@@ -5925,7 +5925,7 @@ impl ChatWidget {
                 self.exit_review_mode_after_item();
             }
             ThreadItem::ContextCompaction { .. } => {
-                self.on_context_compacted();
+                self.add_info_message("Context compacted".to_string(), /*hint*/ None);
             }
             ThreadItem::HookPrompt { .. } => {}
             ThreadItem::CollabAgentToolCall {