Path-only version of embedding-benchmark/SWEbenchCodeRetrieval.
Source code is stripped; only file paths remain. The task: given a GitHub issue
and a repository snapshot represented by its file tree alone, return the file
that needs to be modified.
This is a routing benchmark, not a code retrieval benchmark. It measures how
far path tokens, filenames, extensions, and directory structure get you before
anyone reads a line of source.
