upgrading all other files to be able to use cpu/mps as well as cuda. various minor other changes ,e.g. changing max_iterations to num_iterations in sft script for consistency in naming

run1000.sh

@@ -1,3 +1,5 @@
+#!/bin/bash
+
 # The $1000 tier of nanochat
 # Designed to run end-to-end for $1000/24 ~= 41.6 hours on an 8XH100 node
 # A bit sparser on comments, see speedrun.sh for more detail