feat: 首页改版与 uv / 镜像配置收敛，精简任务数据结构

- 页头只保留品牌与操作图标，三栏改为 1:2:1、容器最宽 1320
- 任务卡片：状态标签移入标题行并缩小，隐藏任务标识，操作行贴内容底边
- uv 配置弹窗：删掉与首页重复的状态条，三段配置改成标签页
- 镜像源：弹窗去掉默认镜像汇总，首页卡片改为展示默认镜像与运行时注入的变量
- 后端：迁移合并为单一基线 0001_init，删掉未生效的 concurrency_policy / retry_*，
  运行触发只剩 schedule / manual；contracts、前端生成类型、README / PLAN 同步

backend/tests/api.rs

@@ -131,6 +131,30 @@ async fn directory_listing_endpoint_returns_subdirectories() {
     );
 }
 
+#[tokio::test]
+async fn directory_listing_endpoint_includes_files_when_requested() {
+    let (app, temp_dir) = test_app().await;
+    let tools = temp_dir.path().join("tools");
+    fs::create_dir_all(tools.join("bin")).expect("bin directory should be created");
+    fs::write(tools.join("uv.exe"), "x").expect("file should be written");
+
+    let uri = format!(
+        "/api/v1/system/directories?path={}&include_files=true",
+        encode_query_path(&tools)
+    );
+    let (status, body) = get_json(&app, &uri).await;
+
+    assert_eq!(status, StatusCode::OK);
+    let entries = body["entries"]
+        .as_array()
+        .expect("entries should be an array");
+    assert_eq!(entries.len(), 2);
+    assert_eq!(entries[0]["name"], "bin");
+    assert_eq!(entries[0]["is_dir"], true);
+    assert_eq!(entries[1]["name"], "uv.exe");
+    assert_eq!(entries[1]["is_dir"], false);
+}
+
 #[tokio::test]
 async fn directory_listing_endpoint_rejects_relative_paths() {
     let (app, _temp_dir) = test_app().await;