feat: 实现日志与调试系统(Debug模块)

- LogLevel: 日志级别枚举 (Verbose, Debug, Info, Warning, Error, Fatal)
- LogCategory: 日志分类 (General, Rendering, Physics, Memory, Threading等)
- ILogSink: 日志输出接口
- ConsoleLogSink: 控制台输出, 支持Windows颜色
- FileLogSink: 文件日志输出
- FileWriter: 文件写入器
- Logger: 日志管理器, 支持多sink, 分类控制
- Profiler: 性能分析器
- 单元测试覆盖

engine/src/Debug/LogCategory.cpp

@@ -0,0 +1,23 @@
+#include "Debug/LogCategory.h"
+
+namespace XCEngine {
+namespace Debug {
+
+const char* LogCategoryToString(LogCategory category) {
+    switch (category) {
+        case LogCategory::General:     return "General";
+        case LogCategory::Rendering:  return "Rendering";
+        case LogCategory::Physics:   return "Physics";
+        case LogCategory::Audio:     return "Audio";
+        case LogCategory::Scripting: return "Scripting";
+        case LogCategory::Network:   return "Network";
+        case LogCategory::Memory:    return "Memory";
+        case LogCategory::Threading: return "Threading";
+        case LogCategory::FileSystem: return "FileSystem";
+        case LogCategory::Custom:    return "Custom";
+        default: return "Unknown";
+    }
+}
+
+} // namespace Debug
+} // namespace XCEngine