Function run_sample 

pub fn run_sample(
    sample: &LocomoSample,
    project_root: &Path,
    top_k: usize,
) -> SampleResult

Ingest a sample’s turns into an isolated knowledge store rooted at project_root, then recall + score each question with top_k memories.

project_root must be unique per sample so the knowledge hashes don’t collide. The caller is responsible for pointing LEAN_CTX_DATA_DIR at a throwaway dir.