feat: 添加Makefile编译系统和BUILD文档

- 创建完整的Makefile支持make编译
- 支持编译控制台版本和GUI版本
- 添加清理、运行、帮助等目标
- 自动处理SDL3和网络库依赖
- 创建BUILD.md编译指南文档
- 完善GUI相关全局变量管理
- 丰富函数注释和文档

Makefile

@@ -0,0 +1,80 @@
+# 五子棋游戏 Makefile
+# 支持编译控制台版本和GUI版本
+
+# 编译器设置
+CC = gcc
+CFLAGS = -Wall -Wextra -std=c17 -O2
+LDFLAGS = -lws2_32
+
+# SDL3路径设置
+SDL3_PATH = D:/settings/SDL/SDL3-3.2.22/x86_64-w64-mingw32
+SDL3_INCLUDE = -I$(SDL3_PATH)/include
+SDL3_LIBS = -L$(SDL3_PATH)/lib -lSDL3 -lmingw32
+
+# 源文件
+COMMON_SOURCES = main.c gobang.c ai.c config.c game_mode.c globals.c \
+                 init_board.c network.c record.c ui.c gui.c type.h
+
+GUI_SOURCES = $(COMMON_SOURCES)
+CONSOLE_SOURCES = $(COMMON_SOURCES)
+
+# 目标文件
+COMMON_OBJECTS = $(patsubst %.c,%.o,$(filter %.c,$(COMMON_SOURCES)))
+
+# 可执行文件
+CONSOLE_TARGET = gobang_console.exe
+GUI_TARGET = gobang_gui.exe
+
+# 默认目标
+all: $(CONSOLE_TARGET) $(GUI_TARGET)
+
+# 控制台版本
+$(CONSOLE_TARGET): $(COMMON_OBJECTS)
+	$(CC) $(CFLAGS) $(SDL3_INCLUDE) -o $@ $^ $(SDL3_LIBS) $(LDFLAGS)
+
+# GUI版本
+$(GUI_TARGET): $(COMMON_OBJECTS)
+	$(CC) $(CFLAGS) $(SDL3_INCLUDE) -o $@ $^ $(SDL3_LIBS) $(LDFLAGS)
+
+# 通用目标文件编译规则（包含SDL3头文件路径，因为多个文件包含gui.h）
+%.o: %.c
+	$(CC) $(CFLAGS) $(SDL3_INCLUDE) -c -o $@ $<
+
+# 清理规则
+clean:
+	del /Q *.o *.exe 2>nul || true
+
+# 只编译控制台版本
+console: $(CONSOLE_TARGET)
+
+# 只编译GUI版本
+gui: $(GUI_TARGET)
+
+# 安装规则（可选）
+install: all
+	@echo Installing executables...
+	copy $(CONSOLE_TARGET) C:\Program Files\Gobang\ 2>nul || echo Install directory not found
+	copy $(GUI_TARGET) C:\Program Files\Gobang\ 2>nul || echo Install directory not found
+
+# 运行控制台版本
+run-console: $(CONSOLE_TARGET)
+	.\$(CONSOLE_TARGET)
+
+# 运行GUI版本
+run-gui: $(GUI_TARGET)
+	.\$(GUI_TARGET)
+
+# 帮助信息
+help:
+	@echo Available targets:
+	@echo   all          - Build both console and GUI versions
+	@echo   console      - Build console version only
+	@echo   gui          - Build GUI version only
+	@echo   clean        - Remove all object files and executables
+	@echo   run-console  - Build and run console version
+	@echo   run-gui      - Build and run GUI version
+	@echo   install      - Install executables to system directory
+	@echo   help         - Show this help message
+
+# 声明伪目标
+.PHONY: all clean console gui install run-console run-gui help