fix: camera tracks player elevation; snap all world objects to terrain

Camera: desired_focus_position.y now directly tracks the player's global Y. The existing smooth lerp on focus_position handles interpolation, so the camera follows the player up hills and down slopes without losing vertical sight. Previously only horizontally-deadzoned XZ was tracked.

jajce_world.gd: expanded terrain-snapping coverage to include all nodes under WorldObjects (ResourceNodes, StorageSites, ActivitySites) and the FortressBlockout's children. Added a type guard so non-Node3D children are safely skipped. This prevents houses, activity props, storage crates, and resource nodes from floating above or sinking below the sculpted terrain surface.

world/jajce/jajce_world.gd

@@ -11,14 +11,25 @@ func _initialize_world_presentation() -> void:
 	var active_camera := get_viewport().get_camera_3d()
 	if active_camera != null:
 		terrain.set_camera(active_camera)
+
 	var groups_to_snap: Array[Node] = []
 	groups_to_snap.append_array($FoliageRoot.get_children())
 	if has_node("FortressBlockout"):
 		groups_to_snap.append($FortressBlockout)
+		groups_to_snap.append_array($FortressBlockout.get_children())
 	for child in $VillageRoot.get_children():
 		groups_to_snap.append(child)
+	if has_node("WorldObjects"):
+		var wo := $WorldObjects
+		for group_name in ["ResourceNodes", "StorageSites", "ActivitySites"]:
+			if wo.has_node(group_name):
+				groups_to_snap.append_array(wo.get_node(group_name).get_children())
+
 	for item in groups_to_snap:
-		var pos: Vector3 = item.global_position
+		if not item is Node3D:
+			continue
+		var node3d := item as Node3D
+		var pos := node3d.global_position
 		var h: float = terrain.data.get_height(pos)
 		if not is_nan(h):
-			item.global_position.y = h
+			node3d.global_position.y = h