v3.42.4

## What changed

Fixes Finding B of #3327: `memory_search({ smart: true })` was reporting SmartRetrieval's internal RRF fusion score in the `similarity` field instead of the underlying retrieval relevance score — e.g. a raw retrieval relevance of `0.8` was showing up as `0.03252247488101534`.

- `similarity` now carries the raw retrieval relevance (matches `smart: false` behavior)
- the fused SmartRetrieval ranking score is now exposed separately as `rankingScore`
- `threshold` behavior is unchanged (still applied pre-RRF/MMR/recency)
- 14 new regression tests across the SmartRetrieval package and MCP handler

Fixed in #3340 (thanks @takagibit18).

Finding A of #3327 (reasoningBank/vectorBackend reporting `enabled:true` but routing through `bridge-fallback`) remains open and unclaimed.

## Note on version history

3.42.1–3.42.3 were published to npm without matching version-bump commits on `main`. Verified their tags (`v3.42.0`, `v3.42.1`, `v3.42.3`) are all ancestors of this release, so 3.42.4 is a strict superset of everything previously shipped.

Co-Authored-By: RuFlo <ruv@ruv.net>