Allow daily background change from multiple local images

Microsoft Edge’s theme background feature is visually appealing but limited by its current implementation. Built in backgrounds are raster based and low resolution, especially noticeable on high-DPI displays. While uploading a custom background allows better quality, only one image may be used, and it disables the "Change daily" toggle.
Problem
Low-resolution raster backgrounds appear pixelated.
Uploading a custom image improves quality but disables daily rotation.
Users cannot upload multiple images to rotate among them.

Proposed Solution
Allow users to upload multiple custom images or a folder.
Enable the “Change daily” feature to rotate among user-supplied images.
Consider higher-res raster or vector-based formats to enhance visual clarity.

Benefits
Personalization: Users can curate their own slideshow-style backgrounds.
Enhanced visuals, especially on high-resolution displays.

Context
I understand this repo may not directly control the feature implementation, but this issue is proposed here for community discussion and tracking since the Edge codebase isn't fully open-source.

This is a proposal in MSEdgeExplainers rather than an implementation issue, and it names no file, test, or entry point. Start by checking whether issue #1121 has an associated explainer or tracking document; done would require clarifying implementation ownership and documenting support for multiple custom images with daily rotation.