Binder: list child Kotlin packages/objects in a module's __dir__ and make them attribute-reachable #35

Reported by pythonx-compose (M2 #9). androidx.compose.ui.Alignment imports via the finder, but before that import androidx.compose.ui.Alignment as an attribute raises AttributeError and dir(androidx.compose.ui) does not list it. Completion lists and IDEs need it.

Decided: a binder module's __dir__ includes its direct child packages/objects (Kotlin names, from the packages the table knows), and attribute access to such a child imports it. Kotlin names only, so no conflict with the naming rule.

Completion: 'Alignment' in dir(androidx.compose.ui) and androidx.compose.ui.Alignment.End work without a prior import; tamper check.