fix: bound detection QA to inference coverage

docs/AI_PIPELINES.md

@@ -548,9 +548,14 @@ Sprint 8C makes persisted detections reviewable:
 - QA results reuse `quality_checks` and `metrics`; no parallel QA persistence system is introduced.
 - Configured-YOLO QA derives its evaluation extent from the persisted tile
   manifest. Tile bounds are transformed from their explicit source CRS to
-  EPSG:4326, unioned, and used to clip candidate/reference populations before
-  canonical footprint-IoU matching. Reference features wholly outside the
-  imagery presented to the model no longer count as false negatives.
+  EPSG:4326 and unioned. The union is first applied as a GiST-backed PostGIS
+  spatial predicate, then used to clip the bounded candidate/reference
+  populations before canonical footprint-IoU matching. Complete source counts
+  remain in QA evidence, but regional geometries outside inference coverage are
+  not materialized in application memory and do not count as false negatives.
+- Canonical one-to-one IoU matching uses an in-memory spatial index only to
+  discard geometries whose envelopes cannot intersect. It does not change the
+  configured IoU threshold, greedy match ownership or persisted metrics.
 - A separate reference-envelope IoU pass is persisted as
   `box_to_footprint_diagnostics`. It quantifies possible matching artifacts from
   comparing rectangular detections with irregular building footprints, but is