tweak(credits): Decouple credits scroll timing from render update

[bobtista]

Summary

• Credits screen scrolling now uses wall-clock time instead of frame counting
• Credits scroll at consistent speed regardless of frame rate

Changes

• Replaced m_framesSinceStarted frame counter with m_lastScrollTime timestamp
• Uses timeGetTime() to measure elapsed time between scroll updates
• Converts original frame-based interval to milliseconds (1 frame = 33ms at 30fps)

Test plan

• Verify credits scroll at the same speed at 30fps and higher frame rates
• Verify credits still scroll smoothly without stuttering

30FPS
https://github.com/user-attachments/assets/0215fd82-49f7-4c7c-9903-c8b0f53eb239

60FPS
https://github.com/user-attachments/assets/a45a847b-1f9d-4642-8ab3-23e30de25c04

[xezon]

I don't like this approach because it is inaccurate. Scrolling should be specified as scroll distance per second and then scale each frame by the render frame rate. Probably better to have a start time, then take new time, calculate position offset, check if position has reached new integer, then continue update, otherwise wait next update and fractional move.

[xezon]

New code looks promising. Does it work?

[bobtista]

It works for me :) Took me a minute to figure out how to use the On Screen Keyboard to get at the numpad keys 😆 and that they don't work while the snipping tool is recording for me. Once I got the FPS up and then started recording it seems as smooth on my machine at either framerate, and it maxed out at 70 something, it's old.