feat: bound climb detection by matched official climbs

Detected climbs no longer absorb an official climb's range: official climbs
matched to the route by coordinates claim their stored start/end range, and
climb detection now runs only in the free regions around them. On ride 263 a
single absorbed Cat 2 ascent is split so creating a first-half official climb
lets the second half be detected on its own.

- ride: add Range, freeRegions, and DetectClimbs(claimed); exclude claimed
  ranges so a climb never overlaps one
- official_climb: MatchClimb now bounds-matches purely by coordinates without
  needing a detected climb; extract geo.Nearest shared helper
- rideanalysis: Analyze builds claimed climbs from matched official climbs and
  detects only in free regions; render official vs unmatched climbs separately

1 files changed, 25 insertions, 0 deletions

diff --git a/geo/geo.go b/geo/geo.go
new file mode 100644
index 0000000..0fcff14
--- /dev/null
+++ b/geo/geo.go
@@ -0,0 +1,25 @@
+package geo
+
+import (
+	"math"
+
+	"github.com/jftuga/geodist"
+)
+
+func DistanceM(a, b geodist.Coord) float64 {
+	_, distanceKm := geodist.HaversineDistance(a, b)
+	return distanceKm * 1000
+}
+
+func Nearest(coords []geodist.Coord, target geodist.Coord) (int, float64) {
+	bestIndex := 0
+	bestDistance := math.Inf(1)
+	for index := 0; index < len(coords); index++ {
+		distance := DistanceM(coords[index], target)
+		if distance < bestDistance {
+			bestIndex = index
+			bestDistance = distance
+		}
+	}
+	return bestIndex, bestDistance
+}