feat: propagate approval request of unsubscribed threads (#9232)

A thread can now be spawned by another thread. In order to process the
approval requests of such sub-threads, we need to detect those event and
show them in the TUI.

This is a temporary solution while the UX is being figured out. This PR
should be reverted once done

codex-rs/tui/src/app_event.rs

@@ -14,6 +14,7 @@ use codex_common::approval_presets::ApprovalPreset;
 use codex_core::protocol::Event;
 use codex_core::protocol::RateLimitSnapshot;
 use codex_file_search::FileMatch;
+use codex_protocol::ThreadId;
 use codex_protocol::openai_models::ModelPreset;
 
 use crate::bottom_pane::ApprovalRequest;
@@ -41,6 +42,10 @@ pub(crate) enum WindowsSandboxFallbackReason {
 #[derive(Debug)]
 pub(crate) enum AppEvent {
     CodexEvent(Event),
+    ExternalApprovalRequest {
+        thread_id: ThreadId,
+        event: Event,
+    },
 
     /// Start a new session.
     NewSession,