- Added a new submodule for inverse kinematics (`external/ik.hpp`) to support 2D/3D skeletons and solvers.
- Introduced the `IK` module with factories for `Skeleton2D`, `Skeleton3D`, `Solver2D`, and `Solver3D`.
- Enhanced the animation system with a new `Animation` module that supports property tweening and frame updates.
- Updated CMake configuration to include the new modules and their dependencies.
- Revised documentation to reflect the new features and usage examples for both IK and animation systems.
These additions significantly expand the engine's capabilities for character animation and movement control.
sunxfancy
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