klieo-eval 2.3.0

# klieo-eval

Recall-quality metrics for klieo memory pipelines.

Status: stable at 2.x

## What

Pure scoring — no I/O, no async, no memory-trait dependency. Hand the
crate a slice of `RecallSample { query, expected, returned_ids }` and
get back a `RecallReport` with:

- `hit_rate` — fraction of queries with any expected id in top-K
- `mean_reciprocal_rank` — mean of `1 / rank-of-first-hit`
- `mean_precision_at_k` — `|expected ∩ top-K| / K`, averaged
- `mean_recall_at_k` — `|expected ∩ top-K| / |expected|`, averaged
- `mean_ndcg_at_k` — normalised discounted cumulative gain, binary
  relevance

The harness lets the caller run recall against any memory pipeline —
Qdrant, sqlite-vec, hybrid GraphRAG — then scores the produced ranking.

## Why

The same fixture-driven quality gate previously hard-coded inside the
`klieo-compliance` regulation-recall integration test is reusable across
every klieo memory pipeline. Centralised, deduped, JSON-serialisable
for CI artefacts.

## Example

```rust
use klieo_eval::{score_recall, RecallSample};

let samples = vec![
    RecallSample::new(
        "ICT risk management",
        vec!["dora-art-5".into(), "dora-art-6".into()],
        vec!["dora-art-5".into(), "ai-act-art-6".into(), "dora-art-6".into()],
    ),
];
let report = score_recall(&samples, 5);
assert!(report.hit_rate() >= 0.9);
assert!(report.mean_ndcg_at_k() > 0.95);
```

## License

MIT.