neovim: fix SignColumn transparency

[soulsoiledit]

Closes #599 .

This does not fully resolve the issue with SignColumn being not transparent, as that behavior is dependent on the option cursorline, as they change the highlight groups used for the sign column. In addition, LineNr is also not transparent and is dependent on both cursorline and relativenumber. I think these issues are to be best resolved later on by #249 by relying on the respective vim highlight groups.

Regardless, this change does fix SignColumn when neither of those options are set.

[trueNAHO]

I verified that this PR builds in all cases:

Tested-by: NAHO <[email protected]>

However, since my setup causes weird colors (regardless of this PR) when enabling these options, I am unsure how valuable my testing is.

@anotherhadi, can you verify and approve whether this PR closes your issue #599?

[anotherhadi]

@anotherhadi, can you verify and approve whether this PR closes your issue #599?

It does not, however I didn't enabled cursorline.

In addition, LineNr is also not transparent and is dependent on both cursorline and relativenumber.

[soulsoiledit]

I did not change anything involving LineNr currently, so that makes sense. Is SignColumn itself transparent though?

[anotherhadi]

Is SignColumn itself transparent though?

No

Here are my related settings:
On commit 118e064

programs.stylix = {
    targets.nixvim.transparentBackground = {
      main = true;
      signColumn = true;
    };
    targets.nixvim.plugin = "base16-nvim";
};

programs.nixvim.opts = {
    signcolumn = "yes";
    cursorline = false;
    number = true;
    relativenumber = true;
};

[soulsoiledit]

That's quite strange, these are my results with mini and base16. Could you post your init.lua?