patch handling for non object extract (browserbase#1295)

# why

currently when importing zod vrom zod/v3, and extracting a non object,
it will throw an error "def is undefined"

# what changed

replace static z.object with factory.object, to ensure we always wrap it
in correct zod versions schema

# test plan

tested locally

Author: tkattkat

.changeset/khaki-women-travel.md

@@ -0,0 +1,5 @@
+---
+"@browserbasehq/stagehand": patch
+---
+
+Patch zod handling of non objects in extract

packages/core/lib/utils.ts

@@ -15,7 +15,7 @@ const zFactories = {
   v3: z3 as unknown as typeof z,
 };
 
-function getZFactory(schema: StagehandZodSchema): typeof z {
+export function getZFactory(schema: StagehandZodSchema): typeof z {
   return isZod4Schema(schema) ? zFactories.v4 : zFactories.v3;
 }
 

packages/core/lib/v3/handlers/extractHandler.ts

@@ -1,10 +1,14 @@
 // lib/v3/handlers/extractHandler.ts
 import { extract as runExtract } from "../../inference";
-import { getZodType, injectUrls, transformSchema } from "../../utils";
+import {
+  getZFactory,
+  getZodType,
+  injectUrls,
+  transformSchema,
+} from "../../utils";
 import { v3Logger } from "../logger";
 import { V3FunctionName } from "../types/public/methods";
 import { captureHybridSnapshot } from "../understudy/a11y/snapshot";
-import { z } from "zod";
 import type { ZodTypeAny } from "zod";
 import { LLMClient } from "../llm/LLMClient";
 import { ExtractHandlerParams } from "../types/private/handlers";
@@ -151,10 +155,11 @@ export class ExtractHandler {
       // Ensure we pass an object schema into inference; wrap non-object schemas
       const isObjectSchema = getZodType(baseSchema) === "object";
       const WRAP_KEY = "value" as const;
+      const factory = getZFactory(baseSchema);
       const objectSchema: StagehandZodObject = isObjectSchema
         ? (baseSchema as StagehandZodObject)
-        : (z.object({
-            [WRAP_KEY]: baseSchema as unknown as ZodTypeAny,
+        : (factory.object({
+            [WRAP_KEY]: baseSchema as ZodTypeAny,
           }) as StagehandZodObject);
 
       const [transformedSchema, urlFieldPaths] =