* Make color0 distinct from background/foreground
The majority of themes have color0 available as a subtle offset from
the background. For flexoki-light, because color0 matched foreground, it
wasn't subtle, and would cause invisible text when used as a background
color (e.g., in text editor rulers). For vantablack, ethereal,
hackerman, and white, color0 matched background and would cause
invisible text when a theme wanted text to be de-emphasized.
This patch makes it consistently a subtle offset from background.
* Make helix selection theme colors more subtle
Helix is more usable if the selection background is subtle. This is
primarily because of [[1]], which makes a bright selection like we had
before often make the foreground text unreadable in the picker preview.
[1]: https://github.com/helix-editor/helix/issues/12405
The White theme's vscode.json specified "White Omarchy" as the theme
name, but the Bjarne.white-theme extension registers the theme as
"White". This mismatch caused omarchy-theme-set-vscode to set
workbench.colorTheme to a non-existent theme name.