//! Backend capability declarations.
//!
//! [`BackendCapabilities`] lets callers discover what a database backend
//! supports at runtime (e.g. whether vector search is available).
/// Describes the capabilities of a database backend.
///
/// Backends that implement [`StorageBackend`](super::traits::StorageBackend)
/// can override the default [`StorageBackend::capabilities`] method to
/// advertise what they support.