Add SPINE_ORG environment variable support to scripts/run. When set,
the value is passed as spine-org-file via --eval before loading spine.el.
Usage:
SPINE_ORG=~/my-books.org ./scripts/run
SPINE_ORG=/work/personal-local/spine/sample-books.org ./scripts/run localhost:9090
When unset, defaults to ~/spine/books.org (existing behavior).