Add matrix4

[YuanSang0512]

No description provided.

[CoraBlack]

不要提交无关文件

[CoraBlack]

类与方法注释应使用 doxygen 文档格式

接下来，我会使用copilot进行功能性上的问题排查

[Copilot]

Pull request overview

This PR introduces new 3x3 and 4x4 matrix implementations to gkit::math (including common transforms/projections) and wires them into the build, along with a new Matrix4 test executable.

Changes:

• Add Matrix4 API + implementation (transform/projection/decomposition helpers).
• Add out-of-line Matrix3 implementation and include both matrix sources in src/math/CMakeLists.txt.
• Minor Vector3/Vector4 operator const-correctness update and a new test_matrix4 executable.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
test/math/test_matrix4.cpp	Adds a standalone Matrix4 test/demo executable exercising many Matrix4 APIs.
src/math/vector4.cpp	Adds definition for Vector4 rvalue-ref constructor.
src/math/vector3.cpp	Adds definition for Vector3 rvalue-ref constructor.
src/math/matrix4.cpp	Adds the full Matrix4 implementation (mul/inverse/projection/etc.).
src/math/matrix3.cpp	Adds the Matrix3 implementation moved out of the header.
src/math/CMakeLists.txt	Registers matrix3.cpp/matrix4.cpp in the math object library build.
include/gkit/math/vector4.hpp	Makes Vector4 +/- operators const.
include/gkit/math/vector3.hpp	Makes Vector3 +/- operators const.
include/gkit/math/matrix4.hpp	Adds the Matrix4 public API.
include/gkit/math/matrix3.hpp	Refactors Matrix3 header to use out-of-line definitions and adds comments.

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[YuanSang0512]

已按照Copilot建议修改，具体效果需要根据相机系统验证