[API]: Define core POD components

[nircoe]

Adds the first POD components for the DoD ECS refactor: transform, velocity, parent, and children. transform carries the real logic (local-space matrix composition, direction vectors, mutators), the rest stay minimal, deferring hierarchy and world-space transforms to a future TransformSystem.

• Add transform component: position/rotation/scale, matrix composition, direction vectors, mutators
• Add velocity component: linear/angular
• Add parent/children components with has_parent()/has_children(), using entity::invalid() as the "no parent" sentinel
• Verify all components as standard-layout via static_assert
• Add TransformTests, ParentTests, ChildrenTests, including a rotate()/rotate_around() composition-order regression test
• Register new test files in tests/CMakeLists.txt and tests/main.cpp
• Fix Windows CI MSVC job by dropping the hardcoded VS2022 generator, letting CMake auto-detect the installed Visual Studio version