[codex] Support bqplot 0.12 and 0.13 WebGL paths

[maartenbreddels]

This PR keeps bqplot-image-gl usable with both bqplot 0.12 and bqplot 0.13.

bqplot 0.13 moved the shared WebGL figure setup out of bqplot and into bqplot-gl. bqplot-image-gl still used the older bqplot 0.12 WebGL API directly, so it could render with 0.12 but failed against 0.13 unless the new renderer hooks were initialized separately.

The frontend now detects the available figure API at runtime. For bqplot 0.12, it calls the existing createWebGLRenderer/update_gl path and keeps using render_gl. For bqplot 0.13, it dynamically loads bqplot-gl, calls its exported initializeBqplotFigure helper, registers the image mark with the shared WebGL mark list, and exposes renderGL as the 0.13 render entry point. The scale helpers also bridge snake_case and camelCase APIs so the same frontend code works across the two bqplot lines.

Packaging changes:

• constrain bqplot to >=0.12,<0.14
• add a bqplot13 extra requiring bqplot-gl>=0.1.1
• keep bqplot-gl optional so bqplot 0.12 users do not need to install it

This depends on bqplot/bqplot-gl#29 for the bqplot 0.13 path. That PR exports initializeBqplotFigure and includes shader files in the bqplot-gl npm package.

Validation performed locally with Solara using --no-open:

• bqplot 0.12.47 environment: installed bqplot-image-gl without bqplot-gl, enabled bqplot and bqplot-image-gl nbextensions, loaded the image-gl smoke app, and confirmed the WebGL image rendered through the legacy bqplot renderer.
• bqplot 0.13.0 environment before bqplot-gl: installed bqplot-image-gl without bqplot-gl, enabled bqplot/bqscales/bqplot-image-gl nbextensions, loaded the smoke app, and confirmed the expected failure: the browser requested bqplot-gl and view creation failed.
• bqplot 0.13.0 environment after bqplot-gl branch: installed bqplot-gl from maartenbreddels/bqplot-gl@codex/export-webgl-figure-init, enabled bqplot-gl, restarted Solara, reloaded the same smoke app, and confirmed the WebGL image rendered cleanly.
• node --check js/lib/imagegl.js && node --check js/lib/index.js
• npx webpack --mode=development

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 39.81%. Comparing base (fa968f8) to head (3ab3742).
⚠️ Report is 17 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #186   +/-   ##
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  Coverage   39.81%   39.81%           
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  Files           8        8           
  Lines         211      211           
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  Hits           84       84           
  Misses        127      127           

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