test: tighten image dimension parser assertion

src/agents/pi-embedded-helpers.isbillingerrormessage.test.ts

@@ -965,10 +965,11 @@ describe("image dimension errors", () => {
     const raw =
       '400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.84.content.1.image.source.base64.data: At least one of the image dimensions exceed max allowed size for many-image requests: 2000 pixels"}}';
     const parsed = parseImageDimensionError(raw);
-    expect(parsed).toMatchObject({
+    expect(parsed).toEqual({
       maxDimensionPx: 2000,
       messageIndex: 84,
       contentIndex: 1,
+      raw,
     });
     expect(isImageDimensionErrorMessage(raw)).toBe(true);
   });