fix: mousemove handler uses global event instead of arrow function parameter e

[Saurabh0Gupta]

In src/Utils.js line 576, the mousemove listener declares parameter e
but reads event.clientX / event.clientY — relying on the non-standard
global window.event instead.

This causes:

• TypeError: Cannot read properties of undefined (reading 'clientX')
  in environments where window.event is unavailable
• mousem shader uniform stuck at vec2(0.0, 0.0) — mouse distortion broken
• Naturally fails in Firefox < 66 and strict module contexts

Fix :-
// Before
const mouseX = event.clientX
const mouseY = event.clientY

// After
const mouseX = e.clientX
const mouseY = e.clientY

[Saurabh0Gupta]

@sheryianscodingschool Kindly review the pull request.