fix(studio): export webcrypto from node-polyfills to fix build

The studio Vite build aliases 'crypto' to mocks/node-polyfills.ts.
@objectstack/runtime imports `webcrypto` from 'crypto', so the polyfill
must export it. Map webcrypto to globalThis.crypto (Web Crypto API)
which provides the same SubtleCrypto/getRandomValues surface in browsers.

Agent-Logs-Url: https://github.com/objectstack-ai/framework/sessions/49abf5ad-ca45-4ce6-b799-657ad8f2cd69

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot

apps/studio/mocks/node-polyfills.ts

@@ -102,3 +102,13 @@ export const rename = async () => {};
 export const renameSync = () => {};
 export const createHash = () => ({ update: () => ({ digest: () => '' }) });
 export const randomUUID = () => '00000000-0000-0000-0000-000000000000';
+
+// node:crypto webcrypto polyfill — maps to the browser's native Web Crypto API.
+// The runtime package uses `import { webcrypto as crypto } from "crypto"` to access
+// SubtleCrypto/getRandomValues; in the browser, globalThis.crypto provides the same surface.
+export const webcrypto =
+  (typeof globalThis !== 'undefined' && (globalThis as any).crypto) || {
+    subtle: undefined,
+    getRandomValues: <T extends ArrayBufferView | null>(array: T): T => array,
+    randomUUID: () => '00000000-0000-0000-0000-000000000000',
+  };