add focus trapping to resource preview side panel

[akolson]

Summary

This pr adds focus trapping to the resource preview side panel displayed when importing resources from other channels. It uses the useFocusTrap composable (implemened by @habibayman, Thank you! 🙂).

Note: This seems like best way to resolve the bug for now, however, ultimately, we'll want to migrate the side panel from Vuetify so we can take advantage of the KFocusTrap component, which won't work out of the box with the current side panel implementation.

Before

After

Screen.Recording.2025-09-18.at.13.07.11.mov

References

Fixes #5269

Reviewer guidance

• Import resource from other channels
• Select a particular resource
• Use the Tab key to navigate the side panel
• observe the behaviour

[marcellamaki]

Code changes are nice and easy to read, and seem like a good approach for the near term, and the focus trap does seem to be working fine. I think in some places the focus outline is getting "lost" briefly (it seems like for some items, there is an extra tab required to move between focuable elements), but I think this is a good improvement, and we can address some other optimizations in follow up. (cc @radinamatic)