Implement a "Show Off" visual effect where the Header Canvas animation accelerates and shifts colors when the Grid is scrolled.

Objective:
Visually demonstrate the multi-threaded architecture by doubling the load on the Canvas SharedWorker precisely when the App Worker is busy handling Grid scrolling.

Implementation:

1. Grid Body: Fire isScrollingChange event.
2. Viewport Controller: Listen to grid scroll state and invoke HeaderCanvas.updateTimeScale(2).
3. Header Canvas:
   • Implement timeScale with smooth easing.
   • Add "Hot" gradients (White/Cyan).
   • Draw a high-intensity overlay pass when timeScale > 1.