Removed AnimationManager from Core, Allow custom animation libraries

[jfboeve]

This pull request introduces a major refactor of animation support in the renderer, decoupling the animation manager from the core package and enabling integration with external animation libraries. It adds comprehensive documentation and migration guides, updates the example and test infrastructure to use the new animation approach, and provides a new example project demonstrating custom animation manager integration.

Animation System Refactor

• Removes AnimationManager and related types from the core package root, requiring explicit import from @lightningjs/renderer/animation and eliminating Node.animate() in favor of user-supplied animation libraries. [1] [2] [3]
• Updates the renderer to support animation-aware texture processing via a global animation reference counter, allowing both internal and external animation libraries to throttle texture uploads for smoother performance. [1] [2]

Documentation and Migration

• Adds ANIMATION.md to guide users on integrating third-party animation libraries and animating nodes/shaders, and a migration guide (migration-3x-to-3.3.md) detailing breaking changes and new animation APIs. [1] [2]

Examples and Test Infrastructure

• Refactors the example test harness to instantiate and wire up the animation manager explicitly, passing an animate function to tests and automation scripts. [1] [2] [3] [4] [5] [6] [7] [8] [9]
• Updates animation-related tests to use the new animate function instead of the removed Node.animate.

New Example Project

• Adds a new example project (docs/example-projects/custom-animation-manager/) that demonstrates integrating AnimeJS with the renderer, including configuration files, build scripts, and a particle animation demo. [1] [2] [3] [4] [5]

These changes modernize animation support, improve documentation, and provide clear migration paths and examples for users transitioning to the new system.

[CLAassistant]

All committers have signed the CLA.