feat(多人游戏): 添加多人游戏功能及相关UI组件

- 在WorldManager中初始化ENetMultiplayerPeer
- 移除EntityBase中冗余的peer初始化
- 添加多人游戏面板及相关输入控件
- 更新难度显示格式为范围表示
- 为主题添加LineEdit字体大小设置

scripts/Contents/Panels/Starter.gd

@@ -12,5 +12,5 @@ func _ready():
 			UIState.closeCurrentPanel()
 	)
 func _physics_process(_delta):
-	levelShow.text = "%s/10" % diffEdit.value
+	levelShow.text = "%d ∈ [%d, %d]" % [diffEdit.value, diffEdit.min_value, diffEdit.max_value]
 	GameRule.difficulty = diffEdit.value

scripts/Statemachine/EntityBase.gd

@@ -104,7 +104,6 @@ var currentStage: int = 0
 var spawnTime: float = 0
 
 func _ready():
-	var peer=ENetMultiplayerPeer.new()
 	spawnTime = WorldManager.getTime()
 	register()
 	var selfStatebar: EntityStateBar = $"%statebar"

scripts/Tools/Managers/WorldManager.gd

@@ -4,11 +4,13 @@ class_name WorldManager
 static var rootNode: Node2D
 static var tree: SceneTree
 static var runningTime: int = 0
+static var peer: ENetMultiplayerPeer
 
 func _ready():
 	tree = get_tree()
 	rootNode = self
 	ComponentManager.init()
+	peer = ENetMultiplayerPeer.new()
 func _physics_process(delta):
 	runningTime += delta * 1000
 	if EntityBase.mobCount() == 0 and runningTime > 3000: