fix: create the update directory for fresh named volumes [CI]

ConfigStore.Write only created the config root, so a new volume without update/ made update offers fail with IO_PathNotFound. Create the parent directory on write and ship an empty update/ in the node images.

backend/fleet/src/Fleet.Hosting/Hosting.cs

@@ -243,7 +243,8 @@ public sealed class ConfigStore
             throw new InvalidOperationException("config files must stay inside the config directory");
         }
 
-        Directory.CreateDirectory(_directory);
+        // 相对路径里的子目录（例如 update/）也要建：新建的命名卷里只有镜像自带的目录
+        Directory.CreateDirectory(Path.GetDirectoryName(path)!);
         string temp = path + ".tmp";
 #pragma warning disable RS0030 // 纯采集边界的唯一豁免点：ConfigStore 只写配置目录，先写临时文件再原子替换
         File.WriteAllBytes(temp, content);

backend/probe/tests/MoShiro.Probe.Tests/ProbeTests.cs

@@ -82,4 +82,20 @@ public sealed class ProbeTests
             Directory.Delete(directory, recursive: true);
         }
     }
+
+    [Fact]
+    public void ConfigStore_CreatesSubdirectories_ForFreshVolumes()
+    {
+        // 新建的命名卷里没有 update/：面板转来的更新清单要能写进去
+        string directory = NewDirectory();
+        try
+        {
+            new ConfigStore(directory).Write("update/offer.manifest", "{}"u8.ToArray());
+            Assert.True(File.Exists(Path.Combine(directory, "update", "offer.manifest")));
+        }
+        finally
+        {
+            Directory.Delete(directory, recursive: true);
+        }
+    }
 }

ci/stage-node-image.py

@@ -59,6 +59,9 @@ def stage(component: str, destination: Path) -> None:
     config = destination / "config"
     config.mkdir()
     (config / ".keep").write_text("", encoding="utf-8")
+    # 更新清单和请求放在这里；空的命名卷第一次挂载时会带上这个目录
+    (config / "update").mkdir()
+    (config / "update" / ".keep").write_text("", encoding="utf-8")
 
 
 def main() -> None: