Extract climb detection into a dedicated climb package

Move climb detection, slope, and Cotacol scoring out of ride into a new
climb package that operates on a geometry-only Route (distances, elevations,
coords). Ride embeds climb.Route and keeps its timing and telemetry columns.

- climb.Detect returns []DetectedClimb (Climb + ride-absolute Start).
- Climb owns its sliced geometry; indices are local, with Start reported at
  the detection boundary for absolute position.
- Detected bounds use core.Interval; freeRegions claim suppression fixed.
- ride no longer builds slices: ClimbFromDist/ClimbFromIndexes/climbFrom and
  ride.Climb/Interval/Range are removed; rideanalysis, mountain_pass MatchClimb,
  and web views are rewired to climb types.
- New internal/routetest builds climb.Route from the ride DSL; ridetest reuses
  it and adds timestamps and telemetry.
- Tests moved to climb (synthetic detection and difficulty) and kept in ride
  for GPX-example integration; ride.comparison detection coverage retained.
- mountain_pass.nearestCrossing now reuses geo.Nearest.

2 files changed, 28 insertions, 29 deletions

diff --git a/mountain_pass/detection.go b/mountain_pass/detection.go
index 40281f3..79e55e4 100644
--- a/mountain_pass/detection.go
+++ b/mountain_pass/detection.go
@@ -5,7 +5,8 @@ import (
 	"math"
 
 	"github.com/jftuga/geodist"
-	"github.com/martinlehoux/biking_home/ride"
+	"github.com/martinlehoux/biking_home/climb"
+	"github.com/martinlehoux/biking_home/geo"
 )
 
 // MountainPass is a pass extracted from OpenStreetMap: a node tagged
@@ -112,9 +113,9 @@ func DetectCrossings(coords []geodist.Coord, distances, elevations []float64, pa
 // MatchClimb returns the pass whose coordinates lie within radiusM of the
 // climb's highest point and whose elevation is within elevationToleranceM of
 // that point's elevation, nearest first. Found is false when no pass matches.
-func MatchClimb(climb ride.Climb, passes []MountainPass, radiusM, elevationToleranceM float64) (MountainPass, bool) {
-	topCoord := climb.TopCoord()
-	topElevation := climb.TopElevationM()
+func MatchClimb(segment climb.Climb, passes []MountainPass, radiusM, elevationToleranceM float64) (MountainPass, bool) {
+	topIndex, topElevation := segment.Top()
+	topCoord := segment.Coords[topIndex]
 	var best MountainPass
 	bestDistanceM := radiusM
 	found := false
@@ -139,21 +140,17 @@ func MatchClimb(climb ride.Climb, passes []MountainPass, radiusM, elevationToler
 }
 
 func nearestCrossing(coords []geodist.Coord, distances, elevations []float64, mountainPass MountainPass) (Crossing, bool) {
-	best := Crossing{Pass: mountainPass, DistanceToM: 1e18}
-	for i := range coords {
-		distanceKm, _ := geodist.HaversineDistance(coords[i], *mountainPass.Coord)
-		distanceM := distanceKm * 1000
-		if distanceM < best.DistanceToM {
-			best.DistanceToM = distanceM
-			best.RideDistanceM = distances[i]
-			best.RideElevation = elevations[i]
-			best.ElevationDiff = absFloat64(elevations[i] - float64(mountainPass.Elevation))
-		}
-	}
-	if best.DistanceToM > 1e17 {
-		return best, false
+	index, distanceM := geo.Nearest(coords, *mountainPass.Coord)
+	if math.IsInf(distanceM, 1) {
+		return Crossing{Pass: mountainPass}, false
 	}
-	return best, true
+	return Crossing{
+		Pass:          mountainPass,
+		DistanceToM:   distanceM,
+		RideDistanceM: distances[index],
+		RideElevation: elevations[index],
+		ElevationDiff: absFloat64(elevations[index] - float64(mountainPass.Elevation)),
+	}, true
 }
 
 func absFloat64(value float64) float64 {
diff --git a/mountain_pass/detection_test.go b/mountain_pass/detection_test.go
index 6318ca3..6b297b5 100644
--- a/mountain_pass/detection_test.go
+++ b/mountain_pass/detection_test.go
@@ -5,8 +5,10 @@ import (
 	"testing"
 
 	"github.com/jftuga/geodist"
+	"github.com/martinlehoux/biking_home/climb"
 	"github.com/martinlehoux/biking_home/internal/dbtest"
 	"github.com/martinlehoux/biking_home/internal/ridetest"
+	"github.com/martinlehoux/biking_home/internal/routetest"
 	"github.com/martinlehoux/biking_home/mountain_pass"
 	"github.com/martinlehoux/biking_home/ride"
 	"github.com/stretchr/testify/assert"
@@ -19,7 +21,7 @@ func TestDetectCrossingsFindsPass(t *testing.T) {
 		Name: "Pas de Magnan", Elevation: 460,
 		Coord: &geodist.Coord{Lat: 43.62, Lon: 5.43},
 	}
-	crossings := mountain_pass.DetectCrossings(r.Coords(), r.Distances(), r.Elevations(), []mountain_pass.MountainPass{pass}, 100, 25)
+	crossings := mountain_pass.DetectCrossings(r.Coords, r.Distances, r.Elevations, []mountain_pass.MountainPass{pass}, 100, 25)
 	assert.Len(t, crossings, 1)
 	assert.Equal(t, "Pas de Magnan", crossings[0].Pass.Name)
 	assert.Less(t, crossings[0].DistanceToM, 10.0)
@@ -42,7 +44,7 @@ func TestLoadMountainPassesAroundRideUsesExpandedBounds(t *testing.T) {
 	require.NoError(t, err)
 
 	route := ridetest.MustRide("1km at 10%", ridetest.StartCoord(43.0, 5.0), ridetest.Heading(0.1, 0.1), ridetest.StartElevation(100), ridetest.Sampling(1000))
-	passes, err := mountain_pass.LoadMountainPassesAroundRide(db, route.Coords(), 10_000)
+	passes, err := mountain_pass.LoadMountainPassesAroundRide(db, route.Coords, 10_000)
 	require.NoError(t, err)
 	require.Len(t, passes, 3)
 	assert.Equal(t, "On route edge", passes[0].Name)
@@ -77,13 +79,13 @@ func TestDetectCrossingsIgnoresDistantPass(t *testing.T) {
 		Name: "Col de la Faucille", Elevation: 1320,
 		Coord: &geodist.Coord{Lat: 46.37, Lon: 6.02},
 	}
-	assert.Empty(t, mountain_pass.DetectCrossings(r.Coords(), r.Distances(), r.Elevations(), []mountain_pass.MountainPass{far}, 100, 25))
+	assert.Empty(t, mountain_pass.DetectCrossings(r.Coords, r.Distances, r.Elevations, []mountain_pass.MountainPass{far}, 100, 25))
 }
 
 func TestDetectCrossingsIgnoresPassWithoutCoordinates(t *testing.T) {
 	r := rideFromPoint(t, 43.62, 5.43, 447)
 	noCoord := mountain_pass.MountainPass{Name: "Col de la Gatasse", Elevation: 120}
-	assert.Empty(t, mountain_pass.DetectCrossings(r.Coords(), r.Distances(), r.Elevations(), []mountain_pass.MountainPass{noCoord}, 100, 25))
+	assert.Empty(t, mountain_pass.DetectCrossings(r.Coords, r.Distances, r.Elevations, []mountain_pass.MountainPass{noCoord}, 100, 25))
 }
 
 func TestDetectCrossingsRequiresElevationAgreement(t *testing.T) {
@@ -92,7 +94,7 @@ func TestDetectCrossingsRequiresElevationAgreement(t *testing.T) {
 		Name: "Pas de Magnan", Elevation: 900,
 		Coord: &geodist.Coord{Lat: 43.62, Lon: 5.43},
 	}
-	assert.Empty(t, mountain_pass.DetectCrossings(r.Coords(), r.Distances(), r.Elevations(), []mountain_pass.MountainPass{pass}, 100, 25))
+	assert.Empty(t, mountain_pass.DetectCrossings(r.Coords, r.Distances, r.Elevations, []mountain_pass.MountainPass{pass}, 100, 25))
 }
 
 // rideFromPoint builds a 1 km ride ending at (latitude, longitude) at the
@@ -144,10 +146,10 @@ func TestMatchClimbNearestOfTwo(t *testing.T) {
 
 // climbFixture builds a 2 km climb from 300 m up to 447 m then back down to
 // 380 m, heading northeast from (43.61, 5.42).
-func climbFixture() ride.Climb {
-	r := ridetest.MustRide("1km at 14.7% | 1km at -6.7%",
-		ridetest.StartCoord(43.61, 5.42),
-		ridetest.StartElevation(300),
-		ridetest.Sampling(1000))
-	return r.ClimbFromDist(0, 2000)
+func climbFixture() climb.Climb {
+	route := routetest.MustRoute("1km at 14.7% | 1km at -6.7%",
+		routetest.StartCoord(43.61, 5.42),
+		routetest.StartElevation(300),
+		routetest.Sampling(1000))
+	return climb.Climb{Route: route}
 }