WIP: feat(scene) initial beauty baseline — terrain textures, sky, foam, mist, foliage, shadows

- Add 3 Terrain3D texture assets (limestone, valley grass, warm soil)
- Sculpt initial Terrain3D heightmap with ridge, valley, waterfall drop
- Replace plain water with emissive-tinged material
- Add foam mesh, mist spheres, and procedural sky with valley fog
- Add 10 StylizedTree instances around village perimeter
- Enable directional light shadows with extended cascade range
- Add tree height snapping to terrain surface
- Add refined scaffold tests for material count, terrain height, foliage, sky, fog
- Add terrain texture PNGs and StylizedTree.tscn scene
- Add generate_jajce_terrain.gd tool

tests/jajce_world_scaffold_test.gd

@@ -22,9 +22,26 @@ func _run() -> void:
 		terrain.data_directory == "res://terrain/jajce/data",
 		"Terrain3D should use dedicated Jajce data"
 	)
+	_check(
+		terrain.assets.get_texture_count() == 3,
+		"Jajce terrain should expose its bounded three-material palette (found %s)"
+		% terrain.assets.get_texture_count()
+	)
+	_check(
+		absf(terrain.data.get_height(Vector3.ZERO)) < 0.1,
+		"Central gameplay area should remain level for current navigation"
+	)
+	_check(
+		terrain.data.get_height(Vector3(-72, 0, 18)) > 10.0,
+		"Authored terrain should raise the western fortress ridge"
+	)
 	_check(world.has_node("WaterRoot"), "JajceWorld should expose WaterRoot")
 	_check(world.has_node("VillageRoot"), "JajceWorld should expose VillageRoot")
 	_check(world.has_node("FoliageRoot"), "JajceWorld should expose FoliageRoot")
+	_check(
+		world.get_node("FoliageRoot").get_child_count() >= 10,
+		"JajceWorld should include restrained authored foliage clusters"
+	)
 	_check(
 		world.has_node("GreyboxLandmarks/FortressBlockout"),
 		"Greybox should include the fortress landmark"
@@ -33,6 +50,18 @@ func _run() -> void:
 		world.has_node("WaterRoot/WaterfallGreybox"),
 		"Greybox should include the waterfall drop"
 	)
+	_check(
+		world.has_node("WaterRoot/WaterfallFoam")
+		and world.has_node("WaterRoot/Mist_01"),
+		"Waterfall should include readable foam and mist layers"
+	)
+	var environment: Environment = (
+		world.get_node("WorldEnvironment") as WorldEnvironment
+	).environment
+	_check(
+		environment.fog_enabled and environment.sky != null,
+		"Jajce environment should provide sky and restrained valley fog"
+	)
 	_check(
 		world.has_node("VillageRoot/MillBlockout")
 		and world.has_node("VillageRoot/BridgeBlockout"),