[App-server] v2 for account/updated and account/logout (#6175)

V2 for `account/updated` and `account/logout` for app server. correspond
to old `authStatusChange` and `LogoutChatGpt` respectively. Followup PRs
will make other v2 endpoints call `account/updated` instead of
`authStatusChange` too.

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

@@ -1,3 +1,4 @@
+use crate::protocol::common::AuthMode;
 use codex_protocol::ConversationId;
 use codex_protocol::account::PlanType;
 use codex_protocol::config_types::ReasoningEffort;
@@ -120,3 +121,9 @@ pub struct UploadFeedbackParams {
 pub struct UploadFeedbackResponse {
     pub thread_id: String,
 }
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+pub struct AccountUpdatedNotification {
+    pub auth_method: Option<AuthMode>,
+}