fix(多人游戏): 修复玩家名称冲突问题并重构加入逻辑

将玩家加入逻辑拆分为两个函数，joinPlayer处理玩家加入，mutexPlayer处理名称冲突检测。当检测到重复名称时自动生成唯一名称。同时确保名称变更后再次检查冲突。

scripts/Contents/Panels/Starter.gd

@@ -18,15 +18,19 @@ var historyStack
 @onready var players: VBoxContainer = $"%players"
 @onready var playersList: VBoxContainer = $"%list"
 
+@rpc("any_peer")
+func mutexPlayer(player: String):
+	if multiplayer.is_server():
+		if getPlayerNames().count(player) > 1:
+			var newName = player + str(randi_range(1000, 99999999999))
+			setPlayerName.rpc(player, newName)
+			setPlayerName(player, newName)
 @rpc("any_peer")
 func joinPlayer(player: String):
 	if multiplayer.is_server():
 		addPlayerName(player)
 		rebuildAllPlayers.rpc(getPlayerNames())
-		if getPlayerNames().has(player):
-			var newName = player + str(randi_range(1000, 99999999999))
-			setPlayerName.rpc(player, newName)
-			setPlayerName(player, newName)
+		mutexPlayer(player)
 @rpc("any_peer")
 func leavePlayer(playerName: String):
 	if multiplayer.is_server():
@@ -96,6 +100,7 @@ func _ready():
 		func(newText):
 			setPlayerName.rpc(getLast.call(1), newText)
 			setPlayerName(getLast.call(1), newText)
+			mutexPlayer.rpc(newText)
 	)
 	setState(MultiplayerState.ConnectionState.DISCONNECTED)
 func _physics_process(_delta):