Fix zod imports with ast-grep namespace import rule

Applied ast-grep rule to convert named zod imports to namespace imports
across the api-contract package for consistency.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packages/api-contract/src/contract.ts

@@ -1,5 +1,5 @@
 import { oc } from "@orpc/contract";
-import { z } from "zod";
+import * as z from "zod";
 import {
   adminAddSiteInputSchema,
   adminCreateOrgInputSchema,