Fix broken links in Math API docs

Fix 30+ broken cross-references in docs/api/math/:
- viewport: viewport-getaspectratio/getrect -> getaspectratio/getrect
- matrix4: ../color/operator-mul -> operator_mul, operator-index -> operator_index
- matrix4/get-*: gettranslation/getscale/getrotation -> get-translation/-scale/-rotation
- vector3 operator links: operator_*_assign -> operator-*-assign
- vector3 operator links: operator_sub/add -> operator-sub/add
- vector3 operator-eq/neq: swap mutual references to use hyphen naming
- vector4: ../plane/constructor-default -> constructor_default
- Linter fixes: aabb and rectint relative paths corrected

docs/api/math/matrix4/get-rotation.md

@@ -37,6 +37,6 @@ Quaternion rotation = transform.GetRotation();
 
 - [Matrix4](matrix4.md) - 返回类总览
 - [Quaternion](../quaternion/quaternion.md) - 四元数类
-- [GetTranslation](gettranslation.md) - 获取平移分量
-- [GetScale](getscale.md) - 获取缩放分量
+- [GetTranslation](get-translation.md) - 获取平移分量
+- [GetScale](get-scale.md) - 获取缩放分量
 - [Decompose](decompose.md) - 分解矩阵