[app-server] feat: add thread_id and turn_id to item and error notifications (#7124)

Add `thread_id` and `turn_id` to `item/started`, `item/completed`, and
`error` notifications. Otherwise the client will have a hard time
knowing which thread & turn (if multiple threads are running in
parallel) a new item/error is for.

Also add `thread_id` to `turn/started` and `turn/completed`.

codex-rs/app-server-protocol/src/protocol/v2.rs

@@ -807,6 +807,8 @@ pub struct TurnError {
 #[ts(export_to = "v2/")]
 pub struct ErrorNotification {
     pub error: TurnError,
+    pub thread_id: String,
+    pub turn_id: String,
 }
 
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
@@ -1118,6 +1120,7 @@ pub struct ThreadStartedNotification {
 #[serde(rename_all = "camelCase")]
 #[ts(export_to = "v2/")]
 pub struct TurnStartedNotification {
+    pub thread_id: String,
     pub turn: Turn,
 }
 
@@ -1134,6 +1137,7 @@ pub struct Usage {
 #[serde(rename_all = "camelCase")]
 #[ts(export_to = "v2/")]
 pub struct TurnCompletedNotification {
+    pub thread_id: String,
     pub turn: Turn,
 }
 
@@ -1142,6 +1146,8 @@ pub struct TurnCompletedNotification {
 #[ts(export_to = "v2/")]
 pub struct ItemStartedNotification {
     pub item: ThreadItem,
+    pub thread_id: String,
+    pub turn_id: String,
 }
 
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
@@ -1149,6 +1155,8 @@ pub struct ItemStartedNotification {
 #[ts(export_to = "v2/")]
 pub struct ItemCompletedNotification {
     pub item: ThreadItem,
+    pub thread_id: String,
+    pub turn_id: String,
 }
 
 // Item-specific progress notifications