fix(shortcuts): 修复 milestone +close 路径并补回归测试

close 命令 API URL 误拼为 {repo_path}/{owner}/milestones/{id}/update_status（Owner 重复、Repo 丢失、缺 /v1），修正为 /v1/{owner}/{repo}/milestones/{id}/update_status；新增 TestMilestoneClose 回归测试。

Co-Authored-By: Claude <noreply@anthropic.com>

shortcuts/milestone/milestone.go

@@ -114,7 +114,7 @@ func Shortcuts() []*common.Shortcut {
 				body := map[string]interface{}{
 					"status": "closed",
 				}
-				env, err := ctx.CallAPI("POST", fmt.Sprintf("%s/%s/milestones/%s/update_status", ctx.RepoPath(), ctx.Owner, id), body)
+				env, err := ctx.CallAPI("POST", fmt.Sprintf("%s/milestones/%s/update_status", v1Path(ctx), id), body)
 				if err != nil {
 					return err
 				}

shortcuts/milestone/milestone_test.go

@@ -115,3 +115,30 @@ func TestMilestoneDelete(t *testing.T) {
 		t.Fatalf("delete failed: %v", err)
 	}
 }
+
+func TestMilestoneClose(t *testing.T) {
+	var closePayload map[string]interface{}
+	server := common.NewTestServer(t, func(w http.ResponseWriter, r *http.Request) {
+		// Regression guard: +close must hit /v1/{owner}/{repo}/milestones/{id}/update_status
+		// (previously malformed to /{owner}/{repo}/{owner}/milestones/{id}/update_status — Owner duplicated, Repo dropped, no /v1).
+		if r.Method == "POST" && r.URL.Path == "/v1/owner/repo/milestones/1/update_status.json" {
+			closePayload = common.DecodeJSON(t, r)
+			common.WriteJSON(t, w, map[string]interface{}{
+				"status":  0,
+				"message": "更新成功",
+			})
+		} else {
+			t.Fatalf("unexpected request: %s %s", r.Method, r.URL.Path)
+		}
+	})
+	defer server.Close()
+
+	ctx := common.NewTestContext(t, server, "owner", "repo", map[string]string{
+		"id": "1",
+	})
+	err := common.RunShortcut(t, Shortcuts(), "close", ctx)
+	if err != nil {
+		t.Fatalf("close failed: %v", err)
+	}
+	common.AssertEqual(t, closePayload["status"], "closed")
+}