feat(nu support): add

This allows things like `:r !ls` to function properly with `nu`, which is not
a POSIX shell. It also makes sure if you change the shell, it uses the default
POSIX shell options.

config/extraConfigLua.nix

@@ -74,11 +74,65 @@ _: {
               desc = "Notify when recording macro",
             })
           '';
+
+        # better nu support in nvim
+        # https://www.kiils.dk/en/blog/2024-06-22-using-nushell-in-neovim/
+        nuSupport = # lua
+          ''
+            local posix_shell_options = {
+              shellcmdflag = "-c",
+              shellpipe = "2>&1 | tee",
+              shellquote = "",
+              shellredir = ">%s 2>&1",
+              shelltemp = true,
+              shellxescape = "",
+              shellxquote = "",
+            }
+
+            local nu_shell_options = {
+              shellcmdflag = "--login --stdin --no-newline -c",
+              shellpipe = "| complete \z
+                           | update stderr { ansi strip } \z
+                           | tee { get stderr | save --force --raw %s } \z
+                           | into record",
+              shellquote = "",
+              shellredir = "out+err> %s",
+              shelltemp = false,
+              shellxescape = "",
+              shellxquote = "",
+            }
+
+            local function set_options(options)
+              for k, v in pairs(options) do
+                vim.opt[k] = v
+              end
+            end
+
+
+            local function apply_shell_options()
+              if vim.opt.shell:get():match("nu$") ~= nil then
+                set_options(nu_shell_options)
+              else
+                set_options(posix_shell_options)
+              end
+            end
+
+            apply_shell_options()
+
+            vim.api.nvim_create_autocmd("OptionSet", {
+              pattern = "shell",
+              callback = function()
+                apply_shell_options()
+              end,
+            })
+          '';
+
       in
       # lua
       ''
         ${clipBoardConfig}
         ${caseChangeFunctions}
+        ${nuSupport}
       '';
   };
 }