v0.42.3.0 feat(search): autocut — score-discontinuity result-sizing (#1663 wave 1) (#1682)

* feat(search): autocut — score-discontinuity result-sizing on the rerank separatrix

Cut the ranked set at the cross-encoder rerank-score cliff instead of a fixed
top-K. Default-ON in reranked modes (balanced/tokenmax), no-op without a
reranker. New pure src/core/search/autocut.ts; mode.ts knobs + reranker_top_n_in
= searchLimit (no unscored tail); query op autocut param; --explain + glossary.

* test(search): autocut pure-fn, agent-surface, behavioral + precision/recall eval gate

Adds autocut.test.ts, query-op-autocut.test.ts, autocut-integration.serial.test.ts
(IRON-RULE behavioral via rerankerFn seam), autocut-eval.test.ts (in-repo
precision-lift-without-recall-regression gate). Updates existing knobsHash/bundle
pins to v=7 + reranker_top_n_in.

* chore: version + changelog + docs for autocut (v0.41.34.0)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* fix(search): autocut preserves alias-hop exact matches + cache-HIT meta (codex P1/P2)

P1: applyAliasHop injects the canonical page after reranking (no rerank_score);
autocut would drop it when cutting on the scored set. applyAutocut gains an
optional preserve predicate; hybrid passes r => r.alias_hit === true.
P2: cache-HIT cachedMeta now carries autocut/adaptive_return/mode/embedding_column.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* chore: bump version to v0.42.3.0 (autocut wave)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* docs: PR titles lead with the version (IRON RULE in CLAUDE.md)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

VERSION

@@ -1 +1 @@
-0.42.2.0
+0.42.3.0