fix(window): set correct window size for lazygit to render (#158)

since `open_floating_window` use async way `vim.defer_fn` to create
window, `lazygit` executed with a sync way of `vim.fn.jobstart` in
`exec_lazygit_command`, it can't get the floating window size at the
banging

before:


https://github.com/user-attachments/assets/771b4099-c398-42b4-a80f-367f2d1305e7



after:


https://github.com/user-attachments/assets/12cb7381-625c-49c3-bf61-0e385ce79c76

lua/lazygit.lua

@@ -59,7 +59,9 @@ local function exec_lazygit_command(cmd)
       command = cmd
     end
 
+    vim.schedule(function()
       vim.fn.jobstart(command, { term = true, on_exit = on_exit })
+    end)
   end
   vim.cmd("startinsert")
 end