Added missing category parent menu entries that other SecuBox modules
depend on:
- admin/secubox/security (Security & Monitoring)
- admin/secubox/network (Network Management)
- admin/secubox/system (System & Performance)
Without these parent menus, individual modules like crowdsec, network-modes,
and system-hub couldn't register their menu entries under admin/secubox/*/
This allows all SecuBox modules to appear in the LuCI menu hierarchy.
Fixes: luci-app-secubox menu structure
