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/vector3/operator-neq.md

@@ -27,4 +27,4 @@ bool notEqual = (a != b);  // true
 ## 相关文档
 
 - [Vector3 类总览](vector3.md) - 返回类总览
-- [`operator==`](operator_eq.md) - 相等比较
+- [`operator!=`](operator-neq.md) - 不等比较