fix: Add Support for images with absolute URLs

[cmumatt]

Description

Fixes issue #1032

This PR provides support for absolute image URLs in Style programs within the IDE and Automator. When a URL is absolute, it is fetched directly and thus bypasses the normal example/roger/local/gist handlers.

Implementation strategy and design decisions

Detect and handle absolute image URLs. Only handle relative URLs using the existing logic in the IDE and Automator.

Checklist

• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new ESLint warnings
• I have reviewed any generated changes to the diagrams/ folder

Open questions

• Local image fetching in the IDE is currently marked as TODO. See issue Local image resolution is not working in IDE #1035. This needs to be implemented in a separate PR.
• Absolute image resolution in the IDE does not use a proxy to bypass CORS. If the web server hosting the image does not provide headers indicating a cross-origin request is allowed (e.g., Access-Control-Allow-Origin: *) then the browser will not fulfill the request and the placeholder image will be displayed instead.

[codecov]

Codecov Report

Merging #1033 (9a0849e) into main (fbb902e) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1033   +/-   ##
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  Coverage   64.18%   64.18%           
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  Files          62       62           
  Lines        7954     7954           
  Branches     1802     1802           
=======================================
  Hits         5105     5105           
  Misses       2733     2733           
  Partials      116      116           

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View logs

[joshsunshine]

@cmumatt Please add a test to the registry that includes Image shapes with href properties corresponding to various absolute URLs.

[joshsunshine]

This doesn't seem to work yet with https://www.cs.cmu.edu/~jssunshi/images/ball.svg

[cmumatt]

@cmumatt Please add a test to the registry that includes Image shapes with href properties corresponding to various absolute URLs.

Thanks! Replaced relative paths with absolute URLs in: packages/examples/src/set-theory-domain/venn-3d.sty

[cmumatt]

This doesn't seem to work yet with https://www.cs.cmu.edu/~jssunshi/images/ball.svg

This is CORS. If the web server allowed the cross-origin request or we implemented a CORS proxy, then the browser would fetch the cross-origin image successfully. I've created a separate issue (#1036) to track CORS concerns.