fix: /dashboard/api-manager renders blank (only sidebar visible) #12066

Description

Navigating directly to /dashboard/api-manager renders a blank page (only the sidebar is visible).

Steps

1. Open the authenticated dashboard.
2. Navigate directly to /dashboard/api-manager.
3. Wait for the page to settle.
4. Inspect rendered content.

Expected

Shows existing gateway API keys (masked) and controls to create/revoke/change scopes.

Actual

Only the dashboard sidebar renders; no API-key table, create button, scopes, or management controls are present.

Impact

Blocks safe discovery of a management-scoped key and terminal access to /api/usage/*.