refactor(git): minor structural cleanups

lua/git/cmd.lua

@@ -188,7 +188,7 @@ end
 ---@param arg_lead string
 ---@param cmd_line string
 ---@return string[]
-function M.complete(arg_lead, cmd_line, _)
+local function complete(arg_lead, cmd_line, _)
     local rest = cmd_line:gsub("^%s*%S+%s*", "", 1)
     local words = vim.split(rest, "%s+", { trimempty = false })
     if #words > 1 then
@@ -208,7 +208,7 @@ function M.setup()
         M.run(opts.fargs)
     end, {
         nargs = "*",
-        complete = M.complete,
+        complete = complete,
         desc = "Run git",
     })
 end