feat(db): idempotent startup normalizer rewriting List values to native JSON

src/ZB.MOM.WW.ScadaBridge.ConfigurationDatabase/MigrationHelper.cs

@@ -47,6 +47,12 @@ public static class MigrationHelper
                     "Apply migrations using 'dotnet ef database update' or the generated SQL scripts before starting in production mode.");
             }
         }
+
+        // Safety-net normalizer: rewrite any already-persisted List attribute values from the
+        // old array-of-strings JSON form to the new native-typed form. Idempotent and never
+        // aborts startup for data reasons (per-row skip + log). Safe even if both central
+        // nodes run it concurrently on startup.
+        await ListValueNormalizer.NormalizeAsync(dbContext, logger, cancellationToken);
     }
 
     private static async Task WaitForDatabaseReadyAsync(