[windows] rename(2) is not atomic

This is a proactive bug report and not an issue right now.

There have been considerations and experiments moving our Windows builds to WSL2. In case that happens, we need to be aware that `rename(2)` is [not atomic](https://toot.cat/@zkat/109973167110793372). We rely on it being atomic for at least compaction and deletion.

Review the reported WSL2 and rename(2) atomicity concern, focusing on the compaction and deletion operations that rely on atomic renames. The issue provides no source files, tests, or implementation target; the work is complete only after the project has a decided and validated mitigation or confirms that the proposed Windows build change will not proceed.

Written by the indexing model from the issue text.