* feat(shadertoy): add proper mouse/touch interaction support
- Fix iMouse uniform to match official Shadertoy specification:
- iMouse.xy only updates while button/touch is held down
- iMouse.zw uses positive values when down, negative when released
- Enables proper click detection via iMouse.z > 0
- Add touch event support for mobile devices:
- touchstart/touchmove/touchend/touchcancel handlers
- Same behavior as mouse events
- Update tool description with mouse interaction documentation
- Update README with:
- Mouse & Touch Interaction feature
- Improved Julia Set example with click detection
- iMouse specification table and usage examples
The iMouse uniform is a core Shadertoy feature used by popular shaders
like Star Nest, raymarching examples, and particle systems.
* style: fix Prettier formatting in shadertoy README
6c5aa52c95