feat: harden isolated Tornado test workflow

src/MBN_STOCK_WEBVIEW.Playout/Configuration/PlayoutOptionsLoader.cs

@@ -25,6 +25,16 @@ public static class PlayoutOptionsLoader
         return options;
     }
 
+    /// <summary>
+    /// Loads only the specified JSON file and deliberately ignores all environment
+    /// overrides. Intended for explicit, reproducible diagnostic commands.
+    /// </summary>
+    public static PlayoutOptions LoadFileOnly(string path)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(path);
+        return LoadJson(path);
+    }
+
     internal static bool IsLiveAuthorizedForThisLaunch() =>
         string.Equals(
             Environment.GetEnvironmentVariable(LiveAuthorizationEnvironmentVariable),