fix(headless): S6 thread standardOutputIsTerminal instead of reading Console inside HeadlessProcessHost

HeadlessProcessHost read System.Console.IsOutputRedirected directly to
pick the console renderer's color mode, which only Program.cs (the
executable's own entry point) should ever touch -- the same reasoning
that already put the stdin probe there. Resolve
standardOutputIsTerminal next to the existing !Console.IsInputRedirected
probe in Program.cs and thread it through HeadlessEntryPoint.Run into
HeadlessProcessHost's constructor as a plain parameter.

StandardOutputIsTerminalParameterControlsColorNotTheRealConsole was
shown to fail with the parameter still unused (useColor still reading
the real Console.IsOutputRedirected, which the test host always
redirects): the standardOutputIsTerminal:true case expected dimmed
lifecycle output but got none, since the real console read forced
useColor=false regardless of what the test passed in.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/AcDream.Headless/HeadlessEntryPoint.cs

@@ -47,7 +47,8 @@ internal static class HeadlessEntryPoint
         TextWriter output,
         TextWriter error,
         CancellationToken cancellationToken,
-        bool standardInputIsTerminal = false)
+        bool standardInputIsTerminal = false,
+        bool standardOutputIsTerminal = false)
     {
         ArgumentNullException.ThrowIfNull(arguments);
         ArgumentNullException.ThrowIfNull(standardInput);
@@ -85,7 +86,8 @@ internal static class HeadlessEntryPoint
                     output,
                     directCredentials:
                         commandLine.DirectCredentials,
-                    consoleEnabled: consoleEnabled);
+                    consoleEnabled: consoleEnabled,
+                    standardOutputIsTerminal: standardOutputIsTerminal);
                 return (int)host.RunAsync(cancellationToken)
                     .GetAwaiter()
                     .GetResult();

src/AcDream.Headless/Hosting/HeadlessProcessHost.cs

@@ -37,7 +37,8 @@ internal sealed class HeadlessProcessHost : IDisposable
         TimeProvider? timeProvider = null,
         IHeadlessProcessContentFactory? contentFactory = null,
         HeadlessDirectCredentials? directCredentials = null,
-        bool consoleEnabled = false)
+        bool consoleEnabled = false,
+        bool standardOutputIsTerminal = false)
     {
         ArgumentNullException.ThrowIfNull(configuration);
         ArgumentNullException.ThrowIfNull(paths);
@@ -163,7 +164,7 @@ internal sealed class HeadlessProcessHost : IDisposable
                 HeadlessSessionHost session = _sessions[0];
                 var renderer = new HeadlessConsoleRenderer(
                     diagnostics,
-                    useColor: !System.Console.IsOutputRedirected);
+                    useColor: standardOutputIsTerminal);
                 consoleRendererSubscription =
                     session.Runtime.Subscribe(renderer);
                 HeadlessConsoleController controller = new(

src/AcDream.Headless/Program.cs

@@ -28,7 +28,8 @@ try
         Console.Out,
         Console.Error,
         cancellation.Token,
-        standardInputIsTerminal: !Console.IsInputRedirected);
+        standardInputIsTerminal: !Console.IsInputRedirected,
+        standardOutputIsTerminal: !Console.IsOutputRedirected);
 }
 finally
 {