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

world/jajce/StylizedTree.tscn

@@ -0,0 +1,30 @@
+[gd_scene load_steps=5 format=3]
+
+[sub_resource type="StandardMaterial3D" id="Material_trunk"]
+albedo_color = Color(0.27, 0.16, 0.09, 1)
+roughness = 0.95
+
+[sub_resource type="CylinderMesh" id="Mesh_trunk"]
+material = SubResource("Material_trunk")
+top_radius = 0.22
+bottom_radius = 0.32
+height = 2.8
+
+[sub_resource type="StandardMaterial3D" id="Material_canopy"]
+albedo_color = Color(0.19, 0.38, 0.17, 1)
+roughness = 0.9
+
+[sub_resource type="SphereMesh" id="Mesh_canopy"]
+material = SubResource("Material_canopy")
+radius = 1.35
+height = 2.4
+
+[node name="StylizedTree" type="Node3D"]
+
+[node name="Trunk" type="MeshInstance3D" parent="."]
+position = Vector3(0, 1.4, 0)
+mesh = SubResource("Mesh_trunk")
+
+[node name="Canopy" type="MeshInstance3D" parent="."]
+position = Vector3(0, 3.2, 0)
+mesh = SubResource("Mesh_canopy")