feat: complete legacy UI and playout parity migration

tools/MBN_STOCK_WEBVIEW.DbWriteSmoke/RedactedDatabaseFailureClassifier.cs

@@ -0,0 +1,64 @@
+#nullable enable
+
+using MMoneyCoderSharp.Data;
+using MBN_STOCK_WEBVIEW.Infrastructure;
+using MySqlConnector;
+using Oracle.ManagedDataAccess.Client;
+
+namespace MBN_STOCK_WEBVIEW.DbWriteSmoke;
+
+/// <summary>
+/// Emits only a provider/type classification. Messages, SQL, credentials,
+/// identifiers, and values deliberately never cross this boundary.
+/// </summary>
+internal static class RedactedDatabaseFailureClassifier
+{
+    internal static string Classify(Exception exception)
+    {
+        ArgumentNullException.ThrowIfNull(exception);
+        foreach (var current in Flatten(exception))
+        {
+            switch (current)
+            {
+                case OracleException oracle:
+                    return "Oracle-" + oracle.Number.ToString(
+                        System.Globalization.CultureInfo.InvariantCulture);
+                case MySqlException mariaDb:
+                    return "MariaDb-" + ((int)mariaDb.ErrorCode).ToString(
+                        System.Globalization.CultureInfo.InvariantCulture);
+                case DatabaseOperationException database:
+                    return database.DataSource + "-" +
+                        (database.ProviderErrorCode?.ToString(
+                            System.Globalization.CultureInfo.InvariantCulture) ?? "none");
+                case ManualFinancialMutationRejectedException rejected:
+                    return "ManualRejected-" + rejected.Reason;
+                case OperatorCatalogConflictException conflict:
+                    return "CatalogConflict-" + conflict.Kind + "-" + conflict.CommandKind;
+            }
+        }
+
+        return exception.GetType().Name;
+    }
+
+    private static IEnumerable<Exception> Flatten(Exception exception)
+    {
+        var pending = new Stack<Exception>();
+        var visited = new HashSet<Exception>(ReferenceEqualityComparer.Instance);
+        pending.Push(exception);
+        while (pending.TryPop(out var current) && visited.Add(current))
+        {
+            yield return current;
+            if (current is AggregateException aggregate)
+            {
+                foreach (var inner in aggregate.InnerExceptions.Reverse())
+                {
+                    pending.Push(inner);
+                }
+            }
+            else if (current.InnerException is not null)
+            {
+                pending.Push(current.InnerException);
+            }
+        }
+    }
+}