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/uv.rs

@@ -197,6 +197,81 @@ async fn uv_settings_mutations_require_token() {
     assert_eq!(body["code"], "FORBIDDEN");
 }
 
+#[tokio::test]
+async fn uv_mirror_is_saved_with_the_settings_and_drives_both_urls() {
+    let (app, _temp_dir) = test_app().await;
+    let token = auth_token(&app).await;
+
+    let (status, body) = send_json(&app, Method::GET, "/api/v1/uv", None, None).await;
+    assert_eq!(status, StatusCode::OK);
+    assert_eq!(
+        body["mirror_url"],
+        "https://mirrors.ustc.edu.cn/github-release"
+    );
+    assert_eq!(
+        body["uv_download_url"],
+        "https://mirrors.ustc.edu.cn/github-release/astral-sh/uv/LatestRelease"
+    );
+    assert_eq!(
+        body["python_mirror_url"],
+        "https://mirrors.ustc.edu.cn/github-release/astral-sh/python-build-standalone/releases/download"
+    );
+    // 解释器镜像作为默认环境变量出现在列表里，可以被显式覆盖
+    assert_eq!(
+        body["env_defaults"]["UV_PYTHON_INSTALL_MIRROR"],
+        "https://mirrors.ustc.edu.cn/github-release/astral-sh/python-build-standalone/releases/download"
+    );
+
+    // 非法镜像地址会被拒绝
+    let (status, body) = send_json(
+        &app,
+        Method::PUT,
+        "/api/v1/uv",
+        Some(&token),
+        Some(json!({
+            "source": "managed",
+            "mirror_url": "ftp://mirror.example"
+        })),
+    )
+    .await;
+    assert_eq!(status, StatusCode::BAD_REQUEST);
+    assert_eq!(body["field"], "url");
+
+    // 保存自定义镜像：两个下载地址都由它派生
+    let (status, saved) = send_json(
+        &app,
+        Method::PUT,
+        "/api/v1/uv",
+        Some(&token),
+        Some(json!({
+            "source": "managed",
+            "mirror_url": "https://mirror.example/github-release/"
+        })),
+    )
+    .await;
+    assert_eq!(status, StatusCode::OK);
+    assert_eq!(saved["mirror_url"], "https://mirror.example/github-release");
+    assert_eq!(
+        saved["uv_download_url"],
+        "https://mirror.example/github-release/astral-sh/uv/LatestRelease"
+    );
+
+    // 传 null 恢复内置默认
+    let (status, restored) = send_json(
+        &app,
+        Method::PUT,
+        "/api/v1/uv",
+        Some(&token),
+        Some(json!({ "source": "managed", "mirror_url": null })),
+    )
+    .await;
+    assert_eq!(status, StatusCode::OK);
+    assert_eq!(
+        restored["mirror_url"],
+        "https://mirrors.ustc.edu.cn/github-release"
+    );
+}
+
 #[tokio::test]
 async fn uv_download_requires_token() {
     let (app, _temp_dir) = test_app().await;