Expand description
Per-backend driver modules, one feature-gated submodule per backend.
The module is pub so the per-backend concrete connection types and
their inline integration tests are reachable, but the connection
constructors are pub(crate): every caller establishes connections
through the synchronous URL-scheme dispatcher connect, which is
the only blocking entry point and the one that owns the private
runtime. Embedders never touch a driver’s async constructor directly.