Add app source and tests

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

lib/Peach/see/docker/manager/ConnectDockerManager.dart

@@ -0,0 +1,22 @@
+import '../../../about/external/data/Docker.dart';
+
+abstract class ConnectDockerManager {
+  /// Docker's state on the server, plus its containers when it's running.
+  void onDockerLoaded(DockerStatus status, List<DockerContainer> containers);
+
+  /// A container action (start/stop/restart/rm) finished.
+  void onActionFinished(String output);
+
+  /// Output to show in a sheet — container logs, or a test run.
+  void onOutputReady(String title, String output);
+
+  /// The install command was resolved for this distro; the screen confirms it
+  /// with the user before anything runs.
+  void onInstallCommandReady(String command);
+
+  /// The Docker install finished; the caller should re-check status.
+  void onInstallFinished();
+
+  /// Something failed with a message worth surfacing inline.
+  void onDockerFailed(String message);
+}