chore: import upstream snapshot with attribution

Sources/ContainerCommands/System/Property/PropertyList.swift

@@ -0,0 +1,54 @@
+//===----------------------------------------------------------------------===//
+// Copyright © 2025-2026 Apple Inc. and the container project authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//===----------------------------------------------------------------------===//
+
+import ArgumentParser
+import ContainerAPIClient
+import ContainerPersistence
+import ContainerPlugin
+import Foundation
+
+enum ListOutputFormat: String, Decodable, ExpressibleByArgument {
+    case json
+    case toml
+}
+
+extension Application {
+    public struct PropertyList: AsyncLoggableCommand {
+        public static let configuration = CommandConfiguration(
+            commandName: "list",
+            abstract: "List system properties",
+            aliases: ["ls"]
+        )
+
+        @Option(name: .long, help: "Format of the output")
+        var format: ListOutputFormat = .toml
+
+        @OptionGroup
+        public var logOptions: Flags.Logging
+
+        public init() {}
+
+        public func run() async throws {
+            let containerSystemConfig: ContainerSystemConfig = try await Application.loadContainerSystemConfig()
+            let output =
+                switch format {
+                case .json: try Output.renderJSON(containerSystemConfig)
+                case .toml: try Output.renderTOML(containerSystemConfig)
+                }
+            Output.emit(output)
+        }
+    }
+}