Split baked animation modules (#38)

Fixes #19

Splits the baked animation implementation into focused fixed-transform, runtime, visual-binding, and asset-baking modules behind the existing public facade. Preserves public APIs, serialized field order, TypePath, plugin registration, schedules, and runtime behavior.

Reviewed-on: #38
Co-authored-by: Álex Román Núñez <eirexe@eirteam.moe>

src/math/mod.rs

@@ -1,4 +1,5 @@
 pub mod int;
 pub mod segment;
 pub mod vec;
+pub mod fixed_transform;
 pub mod vec3;