home: vim: use actual lua files

Since most of the settings are actually just lua in a VimL file.

home/vim/plugin/signtoggle.lua

@@ -0,0 +1,20 @@
+local signtoggle = vim.api.nvim_create_augroup("signtoggle", { clear = true })
+
+-- Only show sign column for the currently focused buffer
+vim.api.nvim_create_autocmd({ "BufEnter", "FocusGained", "WinEnter" }, {
+    pattern = "*",
+    group = signtoggle,
+    command = "setlocal signcolumn=yes",
+})
+vim.api.nvim_create_autocmd({ "BufLeave", "FocusLost", "WinLeave" }, {
+    pattern = "*",
+    group = signtoggle,
+    command = "setlocal signcolumn=yes",
+})
+
+-- Never show the sign column in a terminal buffer
+vim.api.nvim_create_autocmd({ "TermOpen" }, {
+    pattern = "*",
+    group = signtoggle,
+    command = "setlocal signcolumn=no",
+})