chore: rename package from @hykocx/zen to @zen/core

Update all references across source files, documentation, and
configuration to reflect the new package scope and name. This includes
updating `.npmrc` registry config, install instructions, module
examples, and all import path comments throughout the codebase.

src/features/admin/middleware/protect.js

@@ -17,7 +17,7 @@ import { redirect } from 'next/navigation';
  * 
  * @example
  * // In a server component:
- * import { protectAdmin } from '@hykocx/zen/admin';
+ * import { protectAdmin } from '@zen/core/admin';
  * 
  * export default async function AdminPage() {
  *   const session = await protectAdmin();
@@ -47,7 +47,7 @@ async function protectAdmin(options = {}) {
  * @returns {Promise<boolean>} True if user is admin
  * 
  * @example
- * import { isAdmin } from '@hykocx/zen/admin';
+ * import { isAdmin } from '@zen/core/admin';
  * 
  * export default async function Page() {
  *   const admin = await isAdmin();