feat(launcher): prepare Campaign LA11 user gate

tests/AcDream.Launcher.Core.Tests.Fixtures.ConsoleSignalChild/Program.cs

@@ -0,0 +1,54 @@
+using System.Text.Json;
+
+if (args.Length < 4
+    || args[0] != "wait-for-break"
+    || string.IsNullOrWhiteSpace(args[1])
+    || string.IsNullOrWhiteSpace(args[2]))
+{
+    return 64;
+}
+
+string readyPath = Path.GetFullPath(args[1]);
+string breakPath = Path.GetFullPath(args[2]);
+string label = args[3];
+string[] payloadArguments = args.Skip(4).ToArray();
+using var stopped = new ManualResetEventSlim(false);
+ConsoleCancelEventHandler handler = (_, eventArgs) =>
+{
+    if (eventArgs.SpecialKey != ConsoleSpecialKey.ControlBreak)
+    {
+        return;
+    }
+
+    eventArgs.Cancel = true;
+    try
+    {
+        File.WriteAllText(breakPath, label);
+    }
+    finally
+    {
+        stopped.Set();
+    }
+};
+Console.CancelKeyPress += handler;
+try
+{
+    string stdin = Console.In.ReadToEnd();
+    Directory.CreateDirectory(Path.GetDirectoryName(readyPath)!);
+    File.WriteAllText(
+        readyPath,
+        JsonSerializer.Serialize(new
+        {
+            processId = Environment.ProcessId,
+            label,
+            arguments = payloadArguments,
+            stdinLength = stdin.Length,
+            stdinLineCount = stdin.Count(character => character == '\n'),
+        }));
+
+    return stopped.Wait(TimeSpan.FromSeconds(30)) ? 0 : 75;
+}
+finally
+{
+    Console.CancelKeyPress -= handler;
+}