[dev-v5] fix: Popover should consider viewport changes

[MarvinKlein1508]

🐛 Bug Report

#4872 introduced the viewport into the popover component for calculating the position for the dropdown menu. This made the component usable on iOS and iPadOS devices. There is still an issue when the viewport changes it's size. For example when the user chooses to hide the touch screen keyboard.

💻 Repro or Code Sample

https://v5.fluentui-blazor.net/Lists/Autocomplete

🤔 Expected Behavior

The component should react to this changes and recalculate the position accoridngly.

😯 Current Behavior

WhatsApp.Video.2026-05-19.at.12.42.06.mp4

💁 Possible Solution

We probably need to listen for another event. Not sure yet which one. I open this issue here for our todo list.

🔦 Context

🌍 Your Environment

• OS & Device: iPhone 17 Pro Max with iOS 26.4
• Browser Safari
• latest dev-v5 branch