feat(color)!: Add theme.sh detection

Add support for checking if `theme.sh` is installed and if so attempt to
choose a matching theme colour.
Marked as breaking as this is untested outside of my environment

after/plugin/colour.lua

@@ -3,5 +3,28 @@ if not ok then
 	return
 end
 
+-- default colourscheme settings
 vim.o.background = "dark"
 vim.cmd.colorscheme('gruvbox')
+
+local function invertTheme()
+	if vim.o.background == "dark" then
+		vim.o.background = "light"
+	else
+		vim.o.background = "dark"
+	end
+end
+
+vim.keymap.set('n','<leader>i',invertTheme,{desc='Invert colourscheme'})
+
+
+if vim.fn.executable('theme.sh') and vim.fn.exists('~/.config/.theme_history') then
+	local currentTheme = vim.fn.system('theme.sh -l | tail -n1', 'silent'):gsub('\n','')
+	local lightThemes = vim.fn.systemlist('theme.sh --light -l')
+
+	if vim.tbl_contains(lightThemes,currentTheme) then
+		vim.o.background = "light"
+	else
+		vim.o.background = "dark"
+	end
+end