fix(test-runner): stream state-test progress to stderr

RunStateTestFiles was silent until completion, so the CI idle watchdog
killed long state-test chunks as hung. Report per-test progress like the
other runners.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: Marchhill

src/Nethermind/Nethermind.Test.Runner/Program.cs

@@ -364,13 +364,31 @@ private static List<EthereumTestResult> RunStateTestFiles(
             }
         }
 
+        int completedTests = 0;
+        // Keeps stderr alive for CI idle watchdogs; also streams failures as they happen.
+        void ReportProgress(EthereumTestResult result)
+        {
+            int completed = Interlocked.Increment(ref completedTests);
+            if (!result.Pass)
+            {
+                Console.Error.WriteLine($"\x1b[31mFAIL\x1b[0m [{completed}/{testCases.Count}] {result.Name} - {result.Error}");
+                Console.Error.Flush();
+            }
+            else if (completed % ProgressReportTestInterval == 0 || completed == testCases.Count)
+            {
+                Console.Error.WriteLine($"PROGRESS [{completed}/{testCases.Count}]");
+                Console.Error.Flush();
+            }
+        }
+
         if (workers <= 1 || whenTrace != WhenTrace.Never || enableWarmup)
         {
             List<EthereumTestResult> allResults = [];
             foreach ((int index, GeneralStateTest test) in testCases)
             {
                 StateTestsRunner runner = new(whenTrace, traceMemory, traceStack, chainId, filter, enableWarmup, suppressOutput: true);
                 EthereumTestResult result = runner.RunSingleTest(test);
+                ReportProgress(result);
                 allResults.Add(result);
             }
             return allResults;
@@ -385,6 +403,7 @@ private static List<EthereumTestResult> RunStateTestFiles(
                 StateTestsRunner runner = new(WhenTrace.Never, traceMemory, traceStack, chainId, filter, enableWarmup: false, suppressOutput: true);
                 EthereumTestResult result = runner.RunSingleTest(item.test);
                 results[item.index] = result;
+                ReportProgress(result);
             });
 
         return [.. results];