[Feature Request] Read excalidraw support

**Feature Description** Hi, it seems that in #205, you removed support for excalidraw, as it was changing too often. Now, I think it's much more mature and should be stable. Could you add back theming for excalidraw? I don't like how the canvas and embedded images have different background colors than the rest. **Miscellaneous Features** Additional features that may be implemented in the feature but are not necessary per se **Additional context** Add any other context or screenshots about the feature request here. <img width="1292" height="922" alt="Image" src="https://github.com/user-attachments/assets/add7e09e-0f36-49b1-a5e5-5e2f2b7b9059" />