[🐞] (Headless) Carousel inside Modal doesn't honor initial startIndex or selectedIndex binding

[Kesmek]

Which package is affected?

Headless Kit

Describe the bug

When using a Carousel component inside a Modal, the Carousel doesn't honor the initial selectedIndex or startIndex prop when the Modal opens, despite the binding being set correctly. This only occurs when the Carousel is nested inside a Modal - the binding works correctly when the Carousel is used independently outside of a modal. It is more obvious in the repro and example video. Notice how when opening the modal the carousel's index does not match the index of the signal.

nested-carousel-bug.mp4

Reproduction

https://github.com/Kesmek/nested-carousel-bug

Steps to reproduce

1. Clone repro repo
2. Install dependencies
3. bun start
4. Increment selected index to non-zero index
5. Open modal with a nested carousel
6. Carousel opens at index = 0 instead of selected index

System Info

System:
    OS: Linux 6.11 Arch Linux
    CPU: (16) x64 AMD Ryzen 7 7700 8-Core Processor
    Memory: 16.07 GB / 30.47 GB
    Container: Yes
    Shell: 3.7.1 - /usr/bin/fish
  Binaries:
    Node: 23.1.0 - /usr/bin/node
    npm: 10.9.0 - /usr/bin/npm
    pnpm: 9.12.3 - /usr/bin/pnpm
    bun: 1.1.34 - ~/.bun/bin/bun
  npmPackages:
    @builder.io/qwik: ^1.10.0 => 1.10.0 
    @builder.io/qwik-city: ^1.10.0 => 1.10.0 
    @qwik-ui/headless: ^0.6.2 => 0.6.2 
    typescript: 5.4.5 => 5.4.5 
    undici: * => 6.20.1 
    vite: 5.3.5 => 5.3.5

Additional Information

I recognize that this might be a limitation of using modals with stateful components nested inside. If that is the case and it's written in the documentation I will close this issue. Otherwise I think it would be best to state the limitations somewhere clear in the docs.