docs: fix naming conventions across threading, math, memory, core, and debug modules

threading/:
- Rename 19 camelCase method files to hyphenated names
- task-system: createtaskgroup→create-task-group, etc.
- tasksystemconfig: enabletaskprofiling→enable-task-profiling, etc.
- thread: getcurrentid→get-current-id, etc.
- task: addref→add-ref, getid→get-id, etc.

math/:
- Rename underscore operator files to hyphenated
- vector3: operator_add→operator-add, etc.
- matrix4: gettranslation→get-translation, etc.
- vector4: tovector3→to-vector3, constructor_vector3→constructor-vector3
- sphere: sphere_constructor→sphere-constructor, etc.

memory/:
- Remove duplicate memorymanager/ folder (kept manager/ which was correct)

core/:
- filewriter: Consolidate ctor-default.md and ctor-file.md into constructor.md
- Rename dtor.md→destructor.md

debug/:
- filelogsink: Rename construct.md→constructor.md, ~filelogsink.md→destructor.md

All overview pages updated with new file references.

docs/api/threading/task/on-cancel.md

@@ -0,0 +1,38 @@
+# ITask::OnCancel
+
+```cpp
+virtual void OnCancel()
+```
+
+任务取消回调。可在派生类中重写此方法，以在任务被取消时执行清理操作。
+
+**参数：** 无
+
+**返回：** 无
+
+**复杂度：** 取决于具体实现
+
+**示例：**
+
+```cpp
+class NetworkTask : public ITask {
+public:
+    void Execute() override {
+        for (int i = 0; i < 100; ++i) {
+            if (GetStatus() == TaskStatus::Canceled) {
+                return;
+            }
+            SendPacket(i);
+        }
+    }
+    
+    void OnCancel() override {
+        CloseConnection();
+        printf("Network task canceled\n");
+    }
+};
+```
+
+## 相关文档
+
+- [ITask 总览](task.md) - 返回类总览