salvo-database

# Salvo Database Integration

Share a pool via `affix_state::inject(pool)` and pull it out with `depot.obtain::<T>()`.

`depot.obtain::<T>()` returns `Result<&T, _>` (NOT `Option`). Convert to a Salvo error with `.map_err(|_| StatusError::internal_server_error())` or propagate with `?` after conversion.