feat(backups): 主人和管理员可下载单个备份、导出停服世界，字节经一次性票据从导出 Job 流式转给浏览器，备份按 sha256 核对

internal/api/openapi_parity_test.go

@@ -40,6 +40,8 @@ func TestOpenAPISchemasMatchWireStructs(t *testing.T) {
 		"MyServerView":          MyServerView{},
 		"AllowlistEntry":        AllowlistEntry{},
 		"BackupView":            BackupView{},
+		"ExportTicket":          exportTicketView{},
+		"ExportStatus":          exportStatusView{},
 		"Schedule":              Schedule{},
 		"Build":                 build.Build{},
 		"Image":                 build.Image{},