skip the selection-edge query where nothing reads it

The temporal timeline summarises every snapshot in a series. Each summary now
also counts how many features the selection edge cuts, but a timeline point
renders values only, so that was one database round trip per snapshot for a
disclosure nobody sees. Make it opt-out and have the timeline opt out.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

backend/app/services/vector_feature_service.py

@@ -811,6 +811,7 @@ class VectorFeatureService:
         selection_geometry: Any | None = None,
         full_dataset_area: bool = False,
         preclipped_partition_filter: tuple[str, str] | None = None,
+        disclose_selection_edge: bool = True,
     ) -> dict[str, Any]:
         normalized_bbox = VectorFeatureService._normalize_selection_bbox(bbox)
         selection_shape = selection_geometry
@@ -842,7 +843,7 @@ class VectorFeatureService:
         # How many of the counted features the selection edge cuts. Skipped for
         # a pre-clipped whole-area selection, which has no edge to cut against.
         fully_covered_feature_count: int | None = None
-        if not full_dataset_area and feature_count:
+        if disclose_selection_edge and not full_dataset_area and feature_count:
             try:
                 fully_covered_feature_count = int(
                     db.query(func.count(VectorFeature.id))