fix(worker): translate max_turns failure text to English

TaskRunner.BuildFailureMarkdown returned a hardcoded German string for
TerminalReason == "max_turns", the only worker-generated string not in
English. Surfaced as the outcome/roadblock card for one of the most likely
first failures, looking broken to non-German users.

tests/ClaudeDo.Worker.Tests/Runner/FailureDiagnosisTests.cs

@@ -23,7 +23,7 @@ public class FailureDiagnosisTests
         Assert.Contains("55", message);
         Assert.Contains("60", message);
         Assert.Contains("maxTurns", message);
-        Assert.Contains("Queue", message);
+        Assert.Contains("re-queue", message);
         Assert.DoesNotContain(ClaudeProcess.NoResultPrefix, message);
     }
 
@@ -174,12 +174,12 @@ public sealed class FailureDiagnosisEndToEndTests : IDisposable
         using var verify = _db.CreateContext();
         var task = await new TaskRepository(verify).GetByIdAsync("t1");
         Assert.Equal(TaskStatus.Failed, task!.Status);
-        Assert.Contains("Turn-Budget", task.Result);
+        Assert.Contains("Turn budget", task.Result);
         Assert.Contains("60", task.Result);
         Assert.DoesNotContain(ClaudeProcess.NoResultPrefix, task.Result);
 
         var run = await new TaskRunRepository(verify).GetLatestByTaskIdAsync("t1");
-        Assert.Contains("Turn-Budget", run!.ErrorMarkdown);
+        Assert.Contains("Turn budget", run!.ErrorMarkdown);
     }
 
     [Fact]