Add resume_agent collab tool (#10903)

Summary
- add the new resume_agent collab tool path through core, protocol, and
the app server API, including the resume events
- update the schema/TypeScript definitions plus docs so resume_agent
appears in generated artifacts and README
- note that resumed agents rehydrate rollout history without overwriting
their base instructions

Testing
- Not run (not requested)

codex-rs/protocol/src/protocol.rs

@@ -879,6 +879,10 @@ pub enum EventMsg {
     CollabCloseBegin(CollabCloseBeginEvent),
     /// Collab interaction: close end.
     CollabCloseEnd(CollabCloseEndEvent),
+    /// Collab interaction: resume begin.
+    CollabResumeBegin(CollabResumeBeginEvent),
+    /// Collab interaction: resume end.
+    CollabResumeEnd(CollabResumeEndEvent),
 }
 
 impl From<CollabAgentSpawnBeginEvent> for EventMsg {
@@ -929,6 +933,18 @@ impl From<CollabCloseEndEvent> for EventMsg {
     }
 }
 
+impl From<CollabResumeBeginEvent> for EventMsg {
+    fn from(event: CollabResumeBeginEvent) -> Self {
+        EventMsg::CollabResumeBegin(event)
+    }
+}
+
+impl From<CollabResumeEndEvent> for EventMsg {
+    fn from(event: CollabResumeEndEvent) -> Self {
+        EventMsg::CollabResumeEnd(event)
+    }
+}
+
 /// Agent lifecycle status, derived from emitted events.
 #[derive(Debug, Clone, Deserialize, Serialize, PartialEq, Eq, JsonSchema, TS, Default)]
 #[serde(rename_all = "snake_case")]
@@ -2476,6 +2492,29 @@ pub struct CollabCloseEndEvent {
     pub status: AgentStatus,
 }
 
+#[derive(Debug, Clone, Deserialize, Serialize, PartialEq, JsonSchema, TS)]
+pub struct CollabResumeBeginEvent {
+    /// Identifier for the collab tool call.
+    pub call_id: String,
+    /// Thread ID of the sender.
+    pub sender_thread_id: ThreadId,
+    /// Thread ID of the receiver.
+    pub receiver_thread_id: ThreadId,
+}
+
+#[derive(Debug, Clone, Deserialize, Serialize, PartialEq, JsonSchema, TS)]
+pub struct CollabResumeEndEvent {
+    /// Identifier for the collab tool call.
+    pub call_id: String,
+    /// Thread ID of the sender.
+    pub sender_thread_id: ThreadId,
+    /// Thread ID of the receiver.
+    pub receiver_thread_id: ThreadId,
+    /// Last known status of the receiver agent reported to the sender agent after
+    /// resume.
+    pub status: AgentStatus,
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;