ui: enhance scroll snapping and fix physic jitter in Scroller

[deanlee]

Refactors the Scroller's snapping logic to eliminate physics conflicts, fix edge-case bugs, and reduce unnecessary CPU work.

Problems in Previous Snap Logic

• Fighting Physics: It applies the snap offset on top of the scroll panel's momentum every frame. This causes jitter because the physics engine tries to decay velocity while the snapper forces movement.
• Frame Rate Dependency: Dividing by 10 (/ 10) creates inconsistent snapping speeds depending on the FPS.
• Edge Case Bugs: Clamping logic was error-prone, causing issues with small items at the edges.
• Unnecessary CPU Work: All items were scanned every frame, even when already snapped.

Improvements

• Snap logic is now state-aware and only runs once the scroll panel settles (no more fighting physics).
• Snapping is velocity-gated, preventing interference during drag or high-speed flings.
• Snap offset is computed as an absolute target position, not a per-frame delta.
• Clamping uses true scroll bounds, fully fixing edge snap issues.
• When stable, the scroller skips item scanning, saving cycles.

[github-actions]

raylib UI Preview

All Screenshots

[sshane]

This changes how it looks, we want snapping to work with the auto scroll decay so it's a smooth handoff. I agree it's way too complex, all the logic should be in one place