feat: Implement 3D system and procedural texture manager

- Extended mini_math.h with mat4 multiplication and affine transforms.
- Implemented TextureManager for runtime procedural texture generation and GPU upload.
- Added 3D system components: Camera, Object, Scene, and Renderer3D.
- Created test_3d_render mini-demo for interactive 3D verification.
- Fixed WebGPU validation errors regarding depthSlice and unimplemented WaitAny.

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+# 3D system and rendering pipeline
+
+This sub-project describe how the 3D worlds are going to be rendered.
+We want a camera to move around moving and dynamic objects.
+These objects can be need a physics and collision system.
+
+## the idea
+
+Each object has:
+  * a bounding box or capsule
+  * a BVH is maintained while these move around physically (or not)
+  * to render a frame we cull these bounding volumes
+  * at rendering time, the bounding box or sphere is turned into a quad or triangle
+  fan and a shader associated with the object is called (after proper world-object-camera transformations)
+  * each object can be queries for:
+     a) ray-object intersection ("return the distance from the object at this point P in this direction D")
+     b) Signed Distance Field ("what is the minimum distance to the object from this point P?")
+
+So in the end, we'll
+   a) move the camera and lights along paths
+   b) transform the bounding volumes and cull for visible boxes
+   c) project them
+   d) call the objects' respective shaders for rendering
+
+We want to use shadow maps, so multi-passes is expected.
+
+## future step
+
+Have an exporter from Blender modelling software. That would be a converter
+from simple blender-exported files to our internal format (as an asset for
+our AssetManager or as c++ code directly)
+
+## latter improvement
+
+How to handle transparency? Multi-Ray-casting?