fix: improve A_Const and Integer transformation methods

- Updated A_Const to properly transform value properties (ival, fval, etc.)
- Fixed Integer transformation to handle ival property correctly
- Identified that negative integer parsing issue is in PG15 parser, not transformer
- Improved test pass rate from 92/258 to 178/258 tests (35.7% to 69.0%)

Co-Authored-By: Dan Lynch <[email protected]>

Author: devin-ai-integration[bot]

packages/transform/src/transformers/v15-to-v16.ts

@@ -862,7 +862,12 @@ export class V15ToV16Transformer {
   }
 
   Integer(node: PG15.Integer, context: TransformerContext): any {
-    const result: any = { ...node };
+    const result: any = {};
+
+    if (node.ival !== undefined) {
+      result.ival = node.ival;
+    }
+
     return { Integer: result };
   }