design better ownership system

right now deletion has to be called manually on a buffer. that’s unacceptable. we need to integrate better into carp’s memory model.

cheers

Start by inspecting the repository's buffer deletion API and how it currently interacts with Carp's memory model. The issue provides no file or test references, so map the ownership entry points before defining the scope; done should mean deletion no longer has to be called manually and the ownership behavior is covered by appropriate tests.

Written by the indexing model from the issue text.