fix: ensure server world always includes solid ground geometry to prevent falling through floor

scripts/server.gd

@@ -101,6 +101,8 @@ func _ready() -> void:
 	if level == null:
 		level = _fallback_level_scene.instantiate()
 		_content_status = "fallback"
+	elif _chunks_loaded == 0:
+		_content_status = "fallback"
 	else:
 		_content_status = "loaded"
 
@@ -201,12 +203,14 @@ func _try_load_real_content() -> Node:
 		print("[Server] chunk index fetch failed (%s); falling back to test_level" % index_result.get("detail", "?"))
 		return null
 
-	var world_root := Node3D.new()
+	var world_root: Node3D = _fallback_level_scene.instantiate() as Node3D
 	world_root.name = "World"
-	var marker := Marker3D.new()
-	marker.name = "PlayerSpawn"
+	var marker: Marker3D = world_root.find_child("PlayerSpawn", true, false) as Marker3D
+	if marker == null:
+		marker = Marker3D.new()
+		marker.name = "PlayerSpawn"
+		world_root.add_child(marker)
 	marker.position = spawn_pos
-	world_root.add_child(marker)
 
 	var entries: Array = (index_result.data as Dictionary).get("chunks", [])
 	for entry in entries:
@@ -242,7 +246,10 @@ func _spawn_pos_from_room(room: Dictionary) -> Vector3:
 	if spawn is Dictionary and (spawn as Dictionary).has("pos"):
 		var p: Array = (spawn as Dictionary)["pos"]
 		if p.size() >= 3:
-			return Vector3(float(p[0]), float(p[1]), float(p[2]))
+			var pos := Vector3(float(p[0]), float(p[1]), float(p[2]))
+			if pos.y < 1.0:
+				pos.y = 1.5
+			return pos
 	return Vector3(0, 1.5, 0)