### System details

Omarchy 3.2.2

### What's wrong?

With the current ~/.config/nvim/plugin/after/transparency.lua` file in place, running `:checkhealth` or `:LazyHealth` renders the following for the Snacks section if either of the health command are run prior to opening any files with Neovim:

```text
Snacks ~
- ✅ OK setup called
- ❌ ERROR Failed to run healthcheck for "snacks" plugin. Exception:
  ...cal/share/nvim/lazy/snacks.nvim/lua/snacks/util/init.lua:187: attempt to index local 'fg' (a nil value)
```
If I've previously opened a file, then run one of the health commands, I'm getting the following error in the Snacks section:

```text
Snacks ~
- ✅ OK setup called
- ❌ ERROR Failed to run healthcheck for "snacks" plugin. Exception:
  ...r/.local/share/nvim/lazy/snacks.nvim/lua/snacks/init.lua:7: loop or previous error loading module 'snacks.gh'
```

The first error is more helpful for debugging the issue. The problem seems to be that Snacks is trying to blend a color and getting a `nil` value for `fg`:

```lua
-- .local/share/nvim/lazy/snacks.nvim/lua/snacks/util/init.lua

---@param fg string foreground color
---@param bg string background color
---@param alpha number number between 0 and 1. 0 results in bg, 1 results in fg
function M.blend(fg, bg, alpha)
  local bg_rgb = { tonumber(bg:sub(2, 3), 16), tonumber(bg:sub(4, 5), 16), tonumber(bg:sub(6, 7), 16) }
  local fg_rgb = { tonumber(fg:sub(2, 3), 16), tonumber(fg:sub(4, 5), 16), tonumber(fg:sub(6, 7), 16) }
  local blend = function(i)
    local ret = (alpha * fg_rgb[i] + ((1 - alpha) * bg_rgb[i]))
    return math.floor(math.min(math.max(0, ret), 255) + 0.5)
  end
  return string.format("#%02x%02x%02x", blend(1), blend(2), blend(3))
end
```
The `transparency.lua` file doesn't explicitly set `fg`, but I think that its calls to `vim.api.nvim_set_h1` cause the highlight groups to be completely overwritten. So calls like this effectively set `fg` to `nil`:

```lua
vim.api.nvim_set_hl(0, "Normal", { bg = "none" })
```
Commenting out the entire file fixes the issue with the health section's Snacks entry

```text
Snacks ~
- ✅ OK setup called

Snacks.bigfile ~
- ✅ OK setup {enabled}

Snacks.dashboard ~
- ✅ OK setup {enabled}
- ✅ OK setup ran
- ✅ OK dashboard opened

Snacks.explorer ~
- ⚠️ WARNING setup {disabled}
- ✅ OK 'gio' `2.86.2`
- ✅ OK System trash command found

Snacks.image ~
- ✅ OK setup {enabled}
- ✅ OK 'ghostty' `Ghostty 1.2.3-arch2`
- ✅ OK 'magick' `Version: ImageMagick 7.1.2-8 Q16-HDRI x86_64 2300ae543:20251025 https://imagemagick.org`
...
```
The Snacks section of the health page is one of the more useful sections. That's what got me looking into this. 

I'm not confident enough about Neovim hilight groups to make a PR for the issue. I think a fix would be something like:

```lua
local function make_transparent(group)
  local hl = vim.api.nvim_get_hl(0, { name = group })

  -- List of valid nvim_set_hl keys
  local valid_keys = {
    "fg", "bg", "sp", "blend", "bold", "standout", "underline",
    "undercurl", "underdouble", "underdotted", "underdashed",
    "strikethrough", "italic", "reverse", "nocombine", "link",
    "ctermfg", "ctermbg", "cterm"
  }

  local new_hl = {}
  for _, key in ipairs(valid_keys) do
    if key == "bg" then
      new_hl[key] = nil -- Make transparent
    else
      new_hl[key] = hl[key]
    end
  end

  vim.api.nvim_set_hl(0, group, new_hl)
end

local transparent_groups = {
  "Normal",
  "NormalFloat",
  "FloatBorder",
  "Pmenu",
  -- ...
}

for _, group in pairs(transparent_groups) do
  make_transparent(group)
end
```

Looking at this some more, it seems that many of the color schemes (Catppuccin, Tokyonight, Gruvbox) already support transparency. For those themes, I don't think the Omarchy transparency file is needed.