The admin SPA (apps/admin/) has been retired. Its functionality now
lives in apps/app/ under /platform/* routes for super_admin users.
Updated all documentation to reflect: 2 SPAs instead of 3, removed
FRONTEND_ADMIN_URL/port 5173 references, changed production URL from
app.crewli.app to crewli.app. Retired admin-specific security audit
findings (A13-2, A13-4, A13-5, A13-7) and APPS-01 backlog item.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
