Convert private_dot_config/git/config to config.tmpl so that the [user] name/email can be overridden per host/user via the existing `configs` key in .chezmoidata/hosts*.yaml, falling back to the default identity (Xavier Logerais / xavier@logerais.com) when no override is defined. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>