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/vector3/operator-index.md

@@ -0,0 +1,35 @@
+# Vector3::operator[]
+
+```cpp
+float operator[](int index) const
+float& operator[](int index)
+```
+
+通过索引访问向量的分量。0 = x, 1 = y, 2 = z。
+
+**参数：**
+- `index` - 分量索引（0、1 或 2）
+
+**返回：** `float` 或 `float&` - 对应分量的值（const 版本返回值，non-const 版本返回引用）
+
+**异常：** 如果 index 超出范围（< 0 或 > 2），行为未定义
+
+**线程安全：** ✅
+
+**复杂度：** O(1)
+
+**示例：**
+
+```cpp
+Vector3 v(1.0f, 2.0f, 3.0f);
+
+float x = v[0];  // 1.0f
+float y = v[1];  // 2.0f
+float z = v[2];  // 3.0f
+
+v[0] = 10.0f;  // v = (10.0f, 2.0f, 3.0f)
+```
+
+## 相关文档
+
+- [Vector3 类总览](vector3.md) - 返回类总览