page detection and segmentation results instead of returning all of them

/detection/runs/{id}/detections and its GeoJSON sibling returned every
persisted detection, as did the segmentation equivalents. A regional run holds
tens of thousands, and these are the endpoints the results table and the map
overlay call after every run.

They now take limit and offset, default to 2.000, and report total, limit,
offset and truncated so the complete population stays visible while what is
transferred does not. The GeoJSON responses carry the same window in a
geointel_result_window foreign member.

Rows are ordered by confidence, so a capped overlay draws the strongest
detections rather than an arbitrary slice, and the lab says how many of how
many are being shown rather than silently presenting a page as the whole run.

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

docs/API_CONTRACTS.md

@@ -1081,6 +1081,22 @@ Return vector stats (feature counts and geometry summary).
 Return vector bounds and feature count.
 
 
+### Detection and segmentation result windows
+
+`GET /detection/runs/{id}/detections`, `/detection/datasets/{id}/detections`
+and their segmentation equivalents accept `limit` (default 2.000, `0` for
+everything) and `offset`, and return `total`, `limit`, `offset` and
+`truncated`. `total` always describes the complete population; `items` is one
+page of it.
+
+The `/geojson` siblings accept `limit` and report the window in a
+`geointel_result_window` foreign member. Rows are ordered by confidence, so a
+capped overlay draws the strongest detections rather than an arbitrary slice.
+
+A regional run holds tens of thousands of detections, and these are the
+endpoints the results table and the map overlay call after every run; they
+previously returned all of them.
+
 ### GET `/api/v1/projects/{project_id}/quality-checks/{id}/evidence/geojson`
 
 Returns the reviewable geometry behind one quality check: the objects the model