feat(network): 集成ENet库并实现局域网联机对战功能

- 添加ENet库作为网络通信基础，替换原有的原生Socket实现
- 扩展游戏模式支持局域网联机对战（PvP网络模式）
- 重构网络状态结构以适配ENet的Host/Peer模型
- 在图形界面中添加网络对战菜单，支持创建房间和加入房间
- 实现网络消息的发送与接收，包括落子、断开连接等消息类型
- 为网络对战添加定时器轮询机制，实时处理网络事件
- 更新构建系统以编译和链接ENet库

libs/enet/premake4.lua

@@ -0,0 +1,59 @@
+solution "enet"
+	configurations { "Debug", "Release" }
+	platforms { "x32", "x64" }
+
+	project "enet_static"
+		kind "StaticLib"
+		language "C"
+		
+		files { "*.c" }
+		
+		includedirs { "include/" }
+		
+		configuration "Debug"
+			targetsuffix "d"
+			
+			defines({ "DEBUG" })
+
+			flags { "Symbols" }
+		
+		configuration "Release"
+			defines({ "NDEBUG" })
+
+			flags { "Optimize" }
+			
+		configuration { "Debug", "x64" }
+			targetsuffix "64d"
+			
+		configuration { "Release", "x64" }
+			targetsuffix "64"
+
+	project "enet"
+		kind "SharedLib"
+		language "C"
+		
+		files { "*.c" }
+		
+		includedirs { "include/" }
+		
+		defines({"ENET_DLL=1" })
+		
+		configuration "Debug"
+			targetsuffix "d"
+			
+			defines({ "DEBUG" })
+
+			flags { "Symbols" }
+		
+		configuration "Release"
+			defines({ "NDEBUG" })
+
+			flags { "Optimize" }
+			
+		configuration { "Debug", "x64" }
+			targetsuffix "64d"
+			
+		configuration { "Release", "x64" }
+			targetsuffix "64"
+
+