home-manager / nix-managed git configs ship the file from the nix
store, so `git config --global` errors out. catch the failure and
print the equivalent home-manager snippet instead of aborting — the
tea + netrc steps still want to run.
forge-create-token.sh mints an access token for an existing user
(prints to stdout — forgejo only shows it once). forge-login.sh
configures the operator's shell: git config --global user.name /
user.email, ~/.netrc entry for HTTP clones, and `tea login add`
when tea is on PATH. takes the token interactively (hidden input)
so it doesn't land in shell history.
