feat(composition): dive world assembled from a selected site definition

The calibration site spawn sat 16 m from the south bounds edge, inside the
40 m warning margin. The vehicle_test recipe now extends the terrain and
playable bounds 42 m to the south so the spawn is inside the zone.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

tools/sites/vehicle_test_terrain_recipe.gd

@@ -11,7 +11,7 @@ const SitePlacement = preload("res://game/domain/sites/site_placement.gd")
 static func recipe() -> SiteTerrainBaker.Recipe:
 	var result := SiteTerrainBaker.Recipe.new()
 	result.columns = 61
-	result.rows = 69
+	result.rows = 83
 	result.cell_size_m = 3.0
 	result.origin_x_m = -90.0
 	result.origin_z_m = -176.0
@@ -35,7 +35,7 @@ static func definition(terrain: SiteTerrainData) -> DiveSiteDefinition:
 	result.site_id = &"vehicle_test"
 	result.display_name = "Site de calibration du véhicule"
 	result.terrain = terrain
-	result.playable_bounds_m = Rect2(-90.0, -176.0, 180.0, 204.0)
+	result.playable_bounds_m = Rect2(-90.0, -176.0, 180.0, 246.0)
 	result.spawn_position_m = Vector3(0.0, -12.0, 12.0)
 	result.spawn_yaw_radians = 0.0
 	var target := SitePlacement.new()