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/math/vector4/to-vector3.md

@@ -0,0 +1,23 @@
+# Vector4::ToVector3
+
+将 Vector4 转换为 Vector3，丢弃 w 分量。
+
+```cpp
+Vector3 ToVector3() const
+```
+
+**返回：** `Vector3` - 转换后的 Vector3 (x, y, z)
+
+**复杂度：** O(1)
+
+**示例：**
+
+```cpp
+Vector4 pos4(1.0f, 2.0f, 3.0f, 1.0f);
+Vector3 pos3 = pos4.ToVector3();  // (1, 2, 3)
+```
+
+## 相关文档
+
+- [Vector4 总览](vector4.md)
+- [Vector3 总览](../vector3/vector3.md)