Suppress duplicate compaction and terminal wait events (#17601)

Addresses #17514

Problem: PR #16966 made the TUI render the deprecated context-compaction
notification, while v2 could also receive legacy unified-exec
interaction items alongside terminal-interaction notifications, causing
duplicate "Context compacted" and "Waited for background terminal"
messages.

Solution: Suppress deprecated context-compaction notifications and
legacy unified-exec interaction command items from the app-server v2
projection, and render canonical context-compaction items through the
existing TUI info-event path.

codex-rs/tui/src/chatwidget.rs

@@ -2193,6 +2193,7 @@ impl ChatWidget {
         self.request_redraw();
     }
 
+    #[cfg(test)]
     fn on_agent_message(&mut self, message: String) {
         self.finalize_completed_assistant_message(Some(&message));
     }
@@ -5924,7 +5925,7 @@ impl ChatWidget {
                 self.exit_review_mode_after_item();
             }
             ThreadItem::ContextCompaction { .. } => {
-                self.on_agent_message("Context compacted".to_owned());
+                self.on_context_compacted();
             }
             ThreadItem::HookPrompt { .. } => {}
             ThreadItem::CollabAgentToolCall {