fix(VAutocomplete): fix scroll jump #22531

[Kirubapanneers]

fixes #22531

The problem was that itemHeight dropped from 48px to 8.6px after render. That broke the offsets and made the scroll jump to the wrong place.
I fixed it by keeping the first measured itemHeight and not letting it change after that.

Changes

virtual.ts: prevent itemHeight from shrinking after initial measurement
virtual.ts: Reset scrollVelocity to 0 on first scroll after long pause
VAutocomplete.tsx: Fixed scroll timing when menu opens

Steps to reproduce fix

1. Create autocomplete with 500 items
2. Set initial value to Item 100
3. Open menu - should show Item 100
4. Scroll down - should scroll smoothly without jumping

[J-Sek]

I have just took the demo from the original issue to play with it. Tab » Enter » Mouse Up/Down, reload

Screencast.from.2026-03-01.15-16-53.webm

Looks like an improvement (previously it jumped by hundreds).
But we are not done yet.

[Kirubapanneers]

Thanks for checking it out! I’ll look into the remaining issue and since this is my first opensource contribution, I really appreciate the feedback!