WIP: feat(scene) integrate beauty pass — shader water, building blockouts, wind, smoke, 6 textures

- Add 3 missing Terrain3D textures: Dirt Path (id=3), Riverbank Stone (id=4),
  Compacted Ground (id=5) with procedural albedo PNGs + generate tool
- Replace greybox river BoxMesh with animated vertex-displacement water shader
- Replace greybox waterfall BoxMesh with scrolling-UV waterfall shader
- Add WaterfallMist GPUParticles3D with upward drift and alpha fade
- Add wind vertex shader for tree canopies (sin-based, height-weighted sway)
- Replace StylizedTree.tscn with script-driven procedural tree supporting
  3 canopy color variants and position-based randomization
- Replace greybox house boxes with StylizedHouse (walls + pitched roof + door)
- Replace mill box with StylizedMill (body + roof + water wheel cylinder)
- Replace fortress box with FortressBlockout (keep + parapet + corner turret)
- Replace bridge box with BridgeBlockout (deck + pillar supports)
- Add ChimneySmoke GPUParticles3D on each house roof
- Height-snap buildings (fortress + village) to terrain surface in _ready()
- Update JajceWorld.tscn: remove all greybox landmark sub-resources, instance
  new scenes, keep terrain/navigation/sky/fog as-is
- Update scaffold test for new scene structure and beauty elements

world/jajce/jajce_world.gd

@@ -9,7 +9,14 @@ func _initialize_world_presentation() -> void:
 	var active_camera := get_viewport().get_camera_3d()
 	if active_camera != null:
 		terrain.set_camera(active_camera)
-	for tree in $FoliageRoot.get_children():
-		var terrain_height: float = terrain.data.get_height(tree.global_position)
-		if not is_nan(terrain_height):
-			tree.global_position.y = terrain_height
+	var groups_to_snap: Array[Node] = []
+	groups_to_snap.append_array($FoliageRoot.get_children())
+	if has_node("FortressBlockout"):
+		groups_to_snap.append($FortressBlockout)
+	for child in $VillageRoot.get_children():
+		groups_to_snap.append(child)
+	for item in groups_to_snap:
+		var pos := item.global_position
+		var h: float = terrain.data.get_height(pos)
+		if not is_nan(h):
+			item.global_position.y = h