R3 Phase 2 — Per-Strategy Retrieval Quality Breakdown — Implementation Plan (corpus-independent part)

Surface the ensemble's per-strategy ranked lists and add a per-strategy retrieval-quality evaluator (keyword / vector / hybrid / fused / reranked), reusing the Phase 1 IR metrics. Deliver the plumbing + deterministic tests; the real ES measurement over the two-source corpus is a later data task.