Match official climbs against their recorded sample

An official climb matched on endpoint coordinates alone. On a loop ridden
the other way the route meets the climb's top before its bottom, so pairing
each start with the first end inside its lap window credited a 5.9 km
passage as the 850 m Chemin de la Tour Pey Blanc, and a 49 km one on
another ride.

Climbs now keep the sample of the segment they were created from: the
recorded length and elevation gain of the selected route points, captured
by the ride detail and preview handlers and stored NOT NULL. Matching takes
the whole route and drops any candidate outside ±50% of that sample on
either axis, and attempts are refreshed by upsert and prune so re-analyzing
a ride keeps the recorded-at stamp of the passages that survive.

The backfill leaves the web package: backfill.Run recomputes ride values
then official climb attempts as a single `go run . backfill` command
(climbs-backfill is gone), rideanalysis owns the attempt snapshot, and the
mountain-pass loading margin is shared. Applied to the stored rides it
stamps 78 samples, drops the four bogus attempts and leaves ride 800 with
its three Pont Rout passages.

1 files changed, 17 insertions, 0 deletions

diff --git a/climb/route.go b/climb/route.go
index 80a9a43..4ef3465 100644
--- a/climb/route.go
+++ b/climb/route.go
@@ -7,3 +7,20 @@ type Route struct {
 	Elevations []float64
 	Coords     []geodist.Coord
 }
+
+// SegmentSample is a recorded passage: the length and elevation gain ridden between two route points.
+type SegmentSample struct {
+	DistanceM      float64
+	ElevationGainM float64
+}
+
+// Sample returns the recorded length and elevation gain of the route slice between start and end (inclusive), counting only upward steps in the gain.
+func (route Route) Sample(start, end int) SegmentSample {
+	sample := SegmentSample{DistanceM: route.Distances[end] - route.Distances[start]}
+	for i := start + 1; i <= end; i++ {
+		if diff := route.Elevations[i] - route.Elevations[i-1]; diff > 0 {
+			sample.ElevationGainM += diff
+		}
+	}
+	return sample
+}