// Facade modules — namespaced re-exports of the certified Arcature subsystem
// crates. Each module is gated by a Cargo feature so an application that does
// not use a subsystem pays no compile cost, and so the subsystem's APIs do not
// exist on the public surface when the feature is off (engine spec §34).
//
// Modules are namespaced (rather than globbed into the crate root) because
// several siblings re-export the same upstream crate (e.g. `axum` from
// inertia/pages/api, `sqlx` from db/jobs, `serde` from inertia/pages) —
// namespacing avoids glob collisions (engine spec §18). The crate root
// re-exports these module bindings via `pub use facade::*` in `lib.rs`.
//
// One responsibility per file (AGENTS.md §1).