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/CMakeLists.txt

@@ -0,0 +1,119 @@
+cmake_minimum_required(VERSION 2.8.12...3.20)
+
+project(enet)
+
+# The "configure" step.
+include(CheckFunctionExists)
+include(CheckStructHasMember)
+include(CheckTypeSize)
+check_function_exists("fcntl" HAS_FCNTL)
+check_function_exists("poll" HAS_POLL)
+check_function_exists("getaddrinfo" HAS_GETADDRINFO)
+check_function_exists("getnameinfo" HAS_GETNAMEINFO)
+check_function_exists("gethostbyname_r" HAS_GETHOSTBYNAME_R)
+check_function_exists("gethostbyaddr_r" HAS_GETHOSTBYADDR_R)
+check_function_exists("inet_pton" HAS_INET_PTON)
+check_function_exists("inet_ntop" HAS_INET_NTOP)
+check_c_source_compiles("
+    #include <stddef.h>
+    struct S { int a; double b; };
+    int main() {
+    return (int)offsetof(struct S, b);
+    }
+" HAS_OFFSETOF)
+check_struct_has_member("struct msghdr" "msg_flags" "sys/types.h;sys/socket.h" HAS_MSGHDR_FLAGS)
+set(CMAKE_EXTRA_INCLUDE_FILES "sys/types.h" "sys/socket.h")
+check_type_size("socklen_t" HAS_SOCKLEN_T BUILTIN_TYPES_ONLY)
+unset(CMAKE_EXTRA_INCLUDE_FILES)
+if(MSVC)
+	add_definitions(-W3)
+else()
+	add_definitions(-Wno-error)
+endif()
+
+if(HAS_FCNTL)
+    add_definitions(-DHAS_FCNTL=1)
+endif()
+if(HAS_POLL)
+    add_definitions(-DHAS_POLL=1)
+endif()
+if(HAS_GETNAMEINFO)
+    add_definitions(-DHAS_GETNAMEINFO=1)
+endif()
+if(HAS_GETADDRINFO)
+    add_definitions(-DHAS_GETADDRINFO=1)
+endif()
+if(HAS_GETHOSTBYNAME_R)
+    add_definitions(-DHAS_GETHOSTBYNAME_R=1)
+endif()
+if(HAS_GETHOSTBYADDR_R)
+    add_definitions(-DHAS_GETHOSTBYADDR_R=1)
+endif()
+if(HAS_INET_PTON)
+    add_definitions(-DHAS_INET_PTON=1)
+endif()
+if(HAS_INET_NTOP)
+    add_definitions(-DHAS_INET_NTOP=1)
+endif()
+if(HAS_OFFSETOF)
+    add_definitions(-DHAS_OFFSETOF=1)
+endif()
+if(HAS_MSGHDR_FLAGS)
+    add_definitions(-DHAS_MSGHDR_FLAGS=1)
+endif()
+if(HAS_SOCKLEN_T)
+    add_definitions(-DHAS_SOCKLEN_T=1)
+endif()
+
+include_directories(${PROJECT_SOURCE_DIR}/include)
+
+set(INCLUDE_FILES_PREFIX include/enet)
+set(INCLUDE_FILES
+    ${INCLUDE_FILES_PREFIX}/callbacks.h
+    ${INCLUDE_FILES_PREFIX}/enet.h
+    ${INCLUDE_FILES_PREFIX}/list.h
+    ${INCLUDE_FILES_PREFIX}/protocol.h
+    ${INCLUDE_FILES_PREFIX}/time.h
+    ${INCLUDE_FILES_PREFIX}/types.h
+    ${INCLUDE_FILES_PREFIX}/unix.h
+    ${INCLUDE_FILES_PREFIX}/utility.h
+    ${INCLUDE_FILES_PREFIX}/win32.h
+)
+
+set(SOURCE_FILES
+    callbacks.c
+    compress.c
+    host.c
+    list.c
+    packet.c
+    peer.c
+    protocol.c
+    unix.c
+    win32.c)
+
+source_group(include FILES ${INCLUDE_FILES})
+source_group(source FILES ${SOURCE_FILES})
+
+if(WIN32 AND BUILD_SHARED_LIBS AND (MSVC OR CMAKE_CXX_COMPILER_ID MATCHES "Clang"))
+    add_definitions(-DENET_DLL=1)
+    add_definitions(-DENET_BUILDING_LIB)
+endif()
+
+add_library(enet
+    ${INCLUDE_FILES}
+    ${SOURCE_FILES}
+)
+
+if (WIN32)
+    target_link_libraries(enet winmm ws2_32)
+endif()
+
+include(GNUInstallDirs)
+install(TARGETS enet
+    RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
+    ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
+    LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+)
+install(DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/include/enet
+    DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+)