Reconcile recreates route through install_fresh, which pulled
unconditionally: with git.tx1138.com dead, every boot reconcile of
archy-btcpay-db/archy-nbxplorer hard-failed on 'pulling ...' even
though both image:tags sat in local storage the whole time
(live-testing report 2026-07-10). Check image_exists first and only
pull when the ref is truly absent — the same semantics as
ensure_resolved_source_available and the generated quadlets'
Pull=never.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>