[BUG] assetrect images are not reactive

[rexy712]

Describe the bug
When changing the image of a shape of type assetrect, vue elements are not notified of the change. The initiative tracker is the only place I've noticed this issue. This issue exists with and without the initiative reskin PR.

Edit: Also affects the vision tool

To Reproduce
Steps to reproduce the behavior:

1. Add an assetrect shape to initiative.
2. Change the asset of the shape via the shape properties.
3. Image does not update in the initiative tracker.
4. Refreshing the page fetches the new image correctly.

Expected behavior
Since the images are used in ui where reactivity would benefit them, they should be stored reactively somewhere. My first thought was to put the info in PropertiesState, but that doesn't seem good to add a field to everything when only assetrects need the info.

Screenshots

out.mp4

Desktop:

• OS: gentoo linux
• Browser: ungoogled-chromium 139.0.7258.138, firefox 142.0
• Version: dev branch commit 2f0f50e