fix(orm): cast delegate base fields via dialect.fieldRef in policy transformer

Use dialect.fieldRef() for the selection in buildDelegateBaseFieldSelect
so inherited fields with @db.* attributes get the same CAST treatment
as same-model fields.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: ymc9

packages/orm/src/client/crud/dialects/mysql.ts

@@ -323,14 +323,14 @@ export class MySqlCrudDialect<Schema extends SchemaDef> extends LateralJoinDiale
             return 'varchar(191)';
         }
         return match(zmodelType)
-            .with('String', () => 'varchar(191)')
-            .with('Boolean', () => 'tinyint(1)')
+            .with('String', () => 'char')
+            .with('Boolean', () => 'unsigned')
             .with('Int', () => 'signed')
-            .with('BigInt', () => 'bigint')
+            .with('BigInt', () => 'signed')
             .with('Float', () => 'double')
             .with('Decimal', () => 'decimal(65,30)')
             .with('DateTime', () => 'datetime(3)')
-            .with('Bytes', () => 'longblob')
+            .with('Bytes', () => 'binary')
             .with('Json', () => 'json')
             .otherwise(() => undefined);
     }

packages/plugins/policy/src/expression-transformer.ts

@@ -936,7 +936,9 @@ export class ExpressionTransformer<Schema extends SchemaDef> {
             kind: 'SelectQueryNode',
             from: FromNode.create([TableNode.create(baseModel)]),
             selections: [
-                SelectionNode.create(ReferenceNode.create(ColumnNode.create(field), TableNode.create(baseModel))),
+                SelectionNode.create(
+                    this.dialect.fieldRef(baseModel, field, baseModel, false).toOperationNode()
+                ),
             ],
             where: WhereNode.create(
                 conjunction(