The App Bootstrapper (App.php)
The Zero\Core\App class compiles, boots, and routes requests. On load, its unified single-query bootstrap loads both the active Site Tenant and the logged-in User in a single SQL trip, preventing redundant round-trips.
Database Engine (DB.php)
The Zero\Core\DB helper acts as a secure, metadata-safe PDO prepared statements wrapper, blocking SQL Injection vectors natively.