fix: improve Windows custom-state icon contrast

[jsk1004ha]

Summary

Give the Windows locked and shared custom-state icons a light fill with a dark outline. The dual-tone silhouettes remain visible on both light and dark Explorer backgrounds instead of disappearing when a black icon is rendered on the dark theme.

• Shared icon updated to Material Symbols person_add silhouette with light fill and dark outline.
• Locked icon updated with light interior and dark outline.
• All 18 tracked PNG sizes regenerated from updated SVG sources.
• Added automated SVG and PNG contrast regression test (test/testcustomstateicons.cpp).

Fixes #6070.

Validation

• Tested SVG and PNG contrast with automated regression test suite (TestCustomStateIcons).
• Verified dual-tone silhouettes on dark/light themes.
• Verified all 18 tracked PNG assets and SVG sources.
• git diff --check

Assisted-by: ChatGPT:GPT-5.6-Pro

[Rello]

@kra-mo can you check this?

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[kra-mo]

Fair, but the share icon should be a single uniform shape instead of this, which is how it renders for me:

But even better would be to base it off of the same share icon that we use everywhere:

https://fonts.google.com/icons?icon.size=24&icon.color=%231f1f1f&icon.set=Material+Symbols&selected=Material+Symbols+Outlined:person_add:FILL@0;wght@400;GRAD@0;opsz@24&icon.query=person+add

[jsk1004ha]

@kra-mo I updated the shared overlay in e6d9af861337b51f36f99d684fff66e2fe9e62ad to use a single Material Symbols Outlined person_add silhouette, while retaining the white fill and black outline required for light/dark Explorer contrast. I regenerated every tracked shared PNG size (24, 32, 40, 48, 64, 128, 256, 512, and 1024 px) and verified their dimensions plus the presence of both opaque light and dark pixels. The CustomStateIcons regression test added in the preceding commit still covers both SVGs and all 18 raster assets. The GitHub Actions runs are currently marked action_required, so they need the repository-side approval before executing.

[Rello]

is it just me, or are there additional pixels in some icons?

[kra-mo]

@Rello it is not just you

[Rello]

@jsk1004ha can you please check the icons again?

[jsk1004ha]

I checked and found an issue where the icon appeared broken, so I’ve fixed it.

[kra-mo]

Ok, one more thing is that I think it should use the filled variant of the icon, as that looks better as a badge.