Add safety check notification and error handling (#19055)

Adds a new app-server notification that fires when a user account has
been flagged for potential safety reasons.

codex-rs/rollout/src/policy.rs

@@ -138,6 +138,7 @@ fn event_msg_persistence_mode(ev: &EventMsg) -> Option<EventPersistenceMode> {
         | EventMsg::RealtimeConversationRealtime(_)
         | EventMsg::RealtimeConversationClosed(_)
         | EventMsg::ModelReroute(_)
+        | EventMsg::ModelVerification(_)
         | EventMsg::AgentMessageDelta(_)
         | EventMsg::AgentReasoningDelta(_)
         | EventMsg::AgentReasoningRawContentDelta(_)