feat: add memory citation to agent message (#14821)

Client side to come

codex-rs/tui/src/chatwidget/tests.rs

@@ -203,6 +203,7 @@ async fn resumed_initial_messages_render_history() {
             EventMsg::AgentMessage(AgentMessageEvent {
                 message: "assistant reply".to_string(),
                 phase: None,
+                memory_citation: None,
             }),
         ]),
         network_proxy: None,
@@ -251,6 +252,7 @@ async fn thread_snapshot_replay_does_not_duplicate_agent_message_history() {
                     text: "assistant reply".to_string(),
                 }],
                 phase: None,
+                memory_citation: None,
             }),
         }),
     });
@@ -259,6 +261,7 @@ async fn thread_snapshot_replay_does_not_duplicate_agent_message_history() {
         msg: EventMsg::AgentMessage(AgentMessageEvent {
             message: "assistant reply".to_string(),
             phase: None,
+            memory_citation: None,
         }),
     });
 
@@ -1547,6 +1550,7 @@ async fn live_agent_message_renders_during_review_mode() {
         msg: EventMsg::AgentMessage(AgentMessageEvent {
             message: "Review progress update".to_string(),
             phase: None,
+            memory_citation: None,
         }),
     });
 
@@ -1573,6 +1577,7 @@ async fn thread_snapshot_replay_preserves_agent_message_during_review_mode() {
         msg: EventMsg::AgentMessage(AgentMessageEvent {
             message: "Review progress update".to_string(),
             phase: None,
+            memory_citation: None,
         }),
     });
 
@@ -3551,6 +3556,7 @@ fn complete_assistant_message(
                     text: text.to_string(),
                 }],
                 phase,
+                memory_citation: None,
             }),
         }),
     });
@@ -4146,6 +4152,7 @@ async fn live_legacy_agent_message_after_item_completed_does_not_duplicate_assis
         msg: EventMsg::AgentMessage(AgentMessageEvent {
             message: "hello".into(),
             phase: Some(MessagePhase::FinalAnswer),
+            memory_citation: None,
         }),
     });
 
@@ -6010,6 +6017,7 @@ async fn slash_copy_is_unavailable_when_legacy_agent_message_is_not_repeated_on_
         msg: EventMsg::AgentMessage(AgentMessageEvent {
             message: "Legacy final message".into(),
             phase: None,
+            memory_citation: None,
         }),
     });
     let _ = drain_insert_history(&mut rx);
@@ -10855,6 +10863,7 @@ async fn deltas_then_same_final_message_are_rendered_snapshot() {
         msg: EventMsg::AgentMessage(AgentMessageEvent {
             message: "Here is the result.".into(),
             phase: None,
+            memory_citation: None,
         }),
     });