fix[#878]: make all icon backgrounds transparent for dark mode support

[Talhaasif7]

Summary

This PR fixes dark mode issues by replacing all icon background paths using fill="#fff" (white background) with fill="none".
This makes icons display correctly in dark, light, and system themes.

What I Changed

• Updated all /images/svg/*.svg files that used a white background to fill="none".
• Regenerated README.md, REFERENCE.md, and CHECK.html with python3 update_readme.py.
• Verified file sizes remain under 1KB.
• Ran npm test successfully.

Testing

All icons display properly with transparent backgrounds.

Fixes: #878

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✅ Confirmation

• I have read the contributing guidelines
• The icons are each under 1,024 Bytes
• The SVG layout follows the required format:

  <svg xmlns="http://www.w3.org/2000/svg"
  aria-label="..." role="img"
  viewBox="0 0 512 512"><path
  d="m0 0H512V512H0"
  fill="none"/> ... </svg>

[edent]

Have you tested what the images look like on a black background? For example, what does the Auth0 one look like?

[Eiim]

I'm in opposition to this. Some icons simply can't work this way in dark mode: acast, angellist, and apple are obvious cases from a quick glance at the icons in this PR. For some, the white is used as part of the icon and should not be replaced with a different color: bash is a great example. Some icons are already exclusively in dark mode: buffer and codepen are two such cases. Some icons change their own colorways in dark mode: again, bash is an example. If we want to support separate dark and light modes, we'd need to take a more holistic look at it.