build: Add ozz-animation as git submodule

- Added ozz-animation library as external submodule
- Updated .gitmodules configuration
- Integrated ozz-animation into build system

Co-Authored-By: Claude <noreply@anthropic.com>

Author: yohjimane

.gitmodules

@@ -28,3 +28,6 @@
 [submodule "Externals/sse2rvv"]
 	path = Externals/sse2rvv
 	url = https://github.com/pattonkan/sse2rvv.git
+[submodule "Externals/ozz-animation"]
+	path = Externals/ozz-animation
+	url = https://github.com/guillaumeblanc/ozz-animation.git