more audit work

src/__Libraries/StellaOps.Canonical.Json/CanonJson.cs

@@ -176,12 +176,35 @@ public static class CanonJson
                 w.WriteEndArray();
                 break;
 
+            case JsonValueKind.Number:
+                if (TryWriteNormalizedNumber(el, w))
+                {
+                    break;
+                }
+                el.WriteTo(w);
+                break;
+
             default:
                 el.WriteTo(w);
                 break;
         }
     }
 
+    private static bool TryWriteNormalizedNumber(JsonElement element, Utf8JsonWriter writer)
+    {
+        if (element.TryGetDouble(out var doubleValue))
+        {
+            var bits = BitConverter.DoubleToInt64Bits(doubleValue);
+            if (bits == unchecked((long)0x8000000000000000))
+            {
+                writer.WriteNumberValue(0);
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     /// <summary>
     /// Computes SHA-256 hash of bytes, returns lowercase hex string.
     /// </summary>