feat(sites): strata on the Banc du Vigilant drop-off and multi-scale seabed relief

Strata now take a world rectangle, so the 4 m ledges cover the whole break
and talus south of z = 118 m without touching la Saignée or the landmarks.
Roughness gains octave and fractal-type parameters; a SlopeRoughness
modifier roughens rock faces only. Both sites are re-baked with hummocks
from 250 m down to 5 m. The secondary item, the first debris piece and one
safe-route waypoint move a few metres to keep their contracts.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

tools/site_terrain_baker.gd

@@ -410,18 +410,28 @@ class Ripples extends Primitive:
 		return amplitude_m * sin(phase) * falloff
 
 
+## Seeded fractal noise added everywhere. frequency is 1 / wavelength of the largest
+## octave; each further octave halves the wavelength and the amplitude, so a low
+## frequency with five octaves gives hummocks, swales and ripple-scale detail at once.
+## FRACTAL_RIDGED makes sharp crests (rock), FRACTAL_FBM rolling ground (sediment).
 class Roughness extends Primitive:
 	var amplitude_m: float
 	var _noise: FastNoiseLite
 
-	func _init(p_seed: int, p_frequency: float, p_amplitude_m: float) -> void:
+	func _init(
+		p_seed: int,
+		p_frequency: float,
+		p_amplitude_m: float,
+		p_octaves: int = 3,
+		p_fractal_type: FastNoiseLite.FractalType = FastNoiseLite.FRACTAL_FBM
+	) -> void:
 		amplitude_m = p_amplitude_m
 		_noise = FastNoiseLite.new()
 		_noise.noise_type = FastNoiseLite.TYPE_SIMPLEX_SMOOTH
 		_noise.seed = p_seed
 		_noise.frequency = p_frequency
-		_noise.fractal_type = FastNoiseLite.FRACTAL_FBM
-		_noise.fractal_octaves = 3
+		_noise.fractal_type = p_fractal_type
+		_noise.fractal_octaves = p_octaves
 
 	func elevation_delta(x_m: float, z_m: float) -> float:
 		return _noise.get_noise_2d(x_m, z_m) * amplitude_m
@@ -437,12 +447,13 @@ class Modifier extends RefCounted:
 ## Quantises steep ground into horizontal ledges layer_height_m apart: the stratified
 ## walls of a canyon or cliff. Flat floors and summits are below minimum_slope_degrees and
 ## stay untouched; the effect is full from full_slope_degrees. sharpness 0 leaves the
-## field unchanged, 1 cuts hard steps. radius_m 0 applies everywhere.
+## field unchanged, 1 cuts hard steps. region_m is a world-space (x, z) rectangle with a
+## hard edge; an empty rectangle applies everywhere. Ledges need two to three cells of
+## wall per layer to be resolved: at 1.5 m per cell, 4 m layers on a 50 degree wall.
 class Strata extends Modifier:
 	var layer_height_m: float
 	var sharpness: float
-	var centre: Vector2
-	var radius_m: float
+	var region_m: Rect2
 	var _minimum_tangent: float
 	var _full_tangent: float
 
@@ -451,21 +462,19 @@ class Strata extends Modifier:
 		p_sharpness: float,
 		p_minimum_slope_degrees: float,
 		p_full_slope_degrees: float,
-		p_centre: Vector2,
-		p_radius_m: float
+		p_region_m: Rect2
 	) -> void:
 		assert(p_layer_height_m > 0.0, "strata need a positive layer height")
 		layer_height_m = p_layer_height_m
 		sharpness = clampf(p_sharpness, 0.0, 0.999)
-		centre = p_centre
-		radius_m = p_radius_m
+		region_m = p_region_m
 		_minimum_tangent = tan(deg_to_rad(p_minimum_slope_degrees))
 		_full_tangent = tan(deg_to_rad(p_full_slope_degrees))
 
 	func modify(x_m: float, z_m: float, elevation_m: float, gradient: Vector2) -> float:
+		if region_m.has_area() and not region_m.has_point(Vector2(x_m, z_m)):
+			return elevation_m
 		var weight := smoothstep(_minimum_tangent, _full_tangent, gradient.length())
-		if radius_m > 0.0:
-			weight *= 1.0 - smoothstep(radius_m * 0.8, radius_m, Vector2(x_m, z_m).distance_to(centre))
 		if weight <= 0.0:
 			return elevation_m
 		var layer := floorf(elevation_m / layer_height_m)
@@ -474,6 +483,39 @@ class Strata extends Modifier:
 		return lerpf(elevation_m, (layer + sharpened) * layer_height_m, weight)
 
 
+## Seeded noise weighted by the local slope: rock faces and ridge flanks get crumbly
+## while flat sand stays smooth. Zero below minimum_slope_degrees, full amplitude from
+## full_slope_degrees.
+class SlopeRoughness extends Modifier:
+	var amplitude_m: float
+	var _noise: FastNoiseLite
+	var _minimum_tangent: float
+	var _full_tangent: float
+
+	func _init(
+		p_seed: int,
+		p_frequency: float,
+		p_amplitude_m: float,
+		p_minimum_slope_degrees: float,
+		p_full_slope_degrees: float
+	) -> void:
+		amplitude_m = p_amplitude_m
+		_noise = FastNoiseLite.new()
+		_noise.noise_type = FastNoiseLite.TYPE_SIMPLEX_SMOOTH
+		_noise.seed = p_seed
+		_noise.frequency = p_frequency
+		_noise.fractal_type = FastNoiseLite.FRACTAL_RIDGED
+		_noise.fractal_octaves = 3
+		_minimum_tangent = tan(deg_to_rad(p_minimum_slope_degrees))
+		_full_tangent = tan(deg_to_rad(p_full_slope_degrees))
+
+	func modify(x_m: float, z_m: float, elevation_m: float, gradient: Vector2) -> float:
+		var weight := smoothstep(_minimum_tangent, _full_tangent, gradient.length())
+		if weight <= 0.0:
+			return elevation_m
+		return elevation_m + _noise.get_noise_2d(x_m, z_m) * amplitude_m * weight
+
+
 class MaterialPatch extends RefCounted:
 	var centre: Vector2
 	var radius_m: float