fix(ci): use node test environment for encryption tests

Node 20's Web Crypto API rejects JSDOM cross-realm ArrayBuffer objects.
Adding @jest-environment node to encryption.test.ts ensures the tests
run in Node's native environment, bypassing the JSDOM realm mismatch.
These tests don't need a DOM and are pure crypto operations.

Author: pankaj-bind

frontend/src/utils/__tests__/encryption.test.ts

@@ -1,4 +1,8 @@
 // src/utils/__tests__/encryption.test.ts
+/**
+ * @jest-environment node
+ */
+
 /**
  * Client-Side Encryption Unit Tests
  * ═══════════════════════════════════════════════════════════════════════════════