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-sub-assign.md

@@ -25,5 +25,5 @@ v -= Vector3(1.0f, 2.0f, 3.0f);  // v = (4.0f, 5.0f, 6.0f)
 ## 相关文档
 
 - [Vector3 类总览](vector3.md) - 返回类总览
-- [`operator-`](operator_sub.md) - 减法运算
-- [`operator+=`](operator_add_assign.md) - 加法赋值
+- [`operator-`](operator-sub.md) - 减法运算
+- [`operator+=`](operator-add-assign.md) - 加法赋值