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

Client side to come

codex-rs/protocol/src/memory_citation.rs

@@ -0,0 +1,20 @@
+use schemars::JsonSchema;
+use serde::Deserialize;
+use serde::Serialize;
+use ts_rs::TS;
+
+#[derive(Debug, Clone, Default, Serialize, Deserialize, PartialEq, Eq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+pub struct MemoryCitation {
+    pub entries: Vec<MemoryCitationEntry>,
+    pub rollout_ids: Vec<String>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+pub struct MemoryCitationEntry {
+    pub path: String,
+    pub line_start: u32,
+    pub line_end: u32,
+    pub note: String,
+}