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/aabb/aabb.md

@@ -43,5 +43,5 @@ OBB 是可以任意方向旋转的包围盒。
 
 ## 相关文档
 
-- [Bounds](bounds/bounds.md) - 轴对齐包围盒
+- [Bounds](../bounds/bounds.md) - 轴对齐包围盒
 - [Math 模块总览](../math.md)