[app-server] add new account method API stubs (#5527)

These are the schema definitions for the new JSON-RPC APIs associated
with accounts. These are not wired up to business logic yet and will
currently throw an internal error indicating these are unimplemented.

codex-rs/app-server/src/codex_message_processor.rs

@@ -176,6 +176,27 @@ impl CodexMessageProcessor {
             ClientRequest::ListModels { request_id, params } => {
                 self.list_models(request_id, params).await;
             }
+            ClientRequest::LoginAccount {
+                request_id,
+                params: _,
+            } => {
+                self.send_unimplemented_error(request_id, "account/login")
+                    .await;
+            }
+            ClientRequest::LogoutAccount {
+                request_id,
+                params: _,
+            } => {
+                self.send_unimplemented_error(request_id, "account/logout")
+                    .await;
+            }
+            ClientRequest::GetAccount {
+                request_id,
+                params: _,
+            } => {
+                self.send_unimplemented_error(request_id, "account/read")
+                    .await;
+            }
             ClientRequest::ResumeConversation { request_id, params } => {
                 self.handle_resume_conversation(request_id, params).await;
             }
@@ -257,6 +278,15 @@ impl CodexMessageProcessor {
         }
     }
 
+    async fn send_unimplemented_error(&self, request_id: RequestId, method: &str) {
+        let error = JSONRPCErrorError {
+            code: INTERNAL_ERROR_CODE,
+            message: format!("{method} is not implemented yet"),
+            data: None,
+        };
+        self.outgoing.send_error(request_id, error).await;
+    }
+
     async fn login_api_key(&mut self, request_id: RequestId, params: LoginApiKeyParams) {
         if matches!(
             self.config.forced_login_method,