Add edit-in-place script (flakes-oh4v)

Create modules/home/scripts/edit-in-place.bash to back up and replace home-manager managed symlinks with writable copies for local testing

Summary of Changes

Created modules/home/scripts/edit-in-place.bash — autowired automatically. Script backs up the symlink to .bak, removes the symlink, copies .bak back as a regular file, and sets 644 permissions.