Add cloud tasks (#3197)

Adds a TUI for managing, applying, and creating cloud tasks

codex-rs/cloud-tasks/tests/env_filter.rs

@@ -0,0 +1,22 @@
+use codex_cloud_tasks_client::CloudBackend;
+use codex_cloud_tasks_client::MockClient;
+
+#[tokio::test]
+async fn mock_backend_varies_by_env() {
+    let client = MockClient;
+
+    let root = CloudBackend::list_tasks(&client, None).await.unwrap();
+    assert!(root.iter().any(|t| t.title.contains("Update README")));
+
+    let a = CloudBackend::list_tasks(&client, Some("env-A"))
+        .await
+        .unwrap();
+    assert_eq!(a.len(), 1);
+    assert_eq!(a[0].title, "A: First");
+
+    let b = CloudBackend::list_tasks(&client, Some("env-B"))
+        .await
+        .unwrap();
+    assert_eq!(b.len(), 2);
+    assert!(b[0].title.starts_with("B: "));
+}