feat(auth): restrict dashboard, fuentes and datalake to admin role
Fix 1: Main Dashboard link hidden for non-admin users. They only see "Mis Dashboards" which shows widgets filtered by their areas.
Fix 2: "Consultar datos", "Widget Builder" and "Portal Datalake" sidebar links wrapped in isAdmin check — non-admin users won't see these data management tools.
Fix 3 (already implemented): AddWidgetModal already filters AREA_REGISTRY by hasArea(slug), so non-admin users only see widgets from their assigned business areas.
Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com