feat(core)!: introduce runtime extension registry and flat module conventions

BREAKING CHANGE: sup config now derives entries from package.json#exports and a server/client glob instead of manual lists; module structure follows flat + barrel convention with .server.js/.client.js runtime suffixes

src/features/admin/AdminPage.server.js

@@ -1,38 +1,32 @@
-/**
- * Admin Page - Server Component Wrapper for Next.js App Router
- *
- * Re-export this in your app/admin/[...admin]/page.js:
- * export { default } from '@zen/core/features/admin/page';
- */
-
-import { AdminPagesLayout, AdminPagesClient } from '@zen/core/features/admin/pages';
-import { protectAdmin } from '@zen/core/features/admin';
-import { buildNavigationSections } from '@zen/core/features/admin/navigation';
-import { collectAllDashboardData } from './dashboard/serverRegistry.js';
+import AdminShell from './components/AdminShell.js';
+import AdminPageClient from './AdminPage.client.js';
+import { protectAdmin } from './protect.js';
+import { buildNavigationSections } from './navigation.js';
+import { collectWidgetData } from './registry.js';
 import { logoutAction } from '@zen/core/features/auth/actions';
 import { getAppName } from '@zen/core';
+import './widgets/index.server.js';
 
 export default async function AdminPage({ params }) {
   const resolvedParams = await params;
   const session = await protectAdmin();
   const appName = getAppName();
 
-  const dashboardStats = await collectAllDashboardData();
-
+  const widgetData = await collectWidgetData();
   const navigationSections = buildNavigationSections('/');
 
   return (
-    <AdminPagesLayout
+    <AdminShell
       user={session.user}
       onLogout={logoutAction}
       appName={appName}
       navigationSections={navigationSections}
     >
-      <AdminPagesClient
+      <AdminPageClient
         params={resolvedParams}
         user={session.user}
-        dashboardStats={dashboardStats}
+        widgetData={widgetData}
       />
-    </AdminPagesLayout>
+    </AdminShell>
   );
 }