- VPS-hop attic push now runs via sudo so attic reads root's config
(~/.config/attic) which has the imrnes-ts server (Tailscale). Without
it the push ran as the CI user whose config only has pub ->
'Server imrnes-ts does not exist', silently skipping the cache upload.
- Direct push retried 3x (attic push is idempotent): a transient 502
(e.g. atticd restart mid-push, Traefik blip) no longer aborts the
whole closure upload before falling back to VPS-hop.
- Restore $VPS_USER in the 3 ssh:// nix copy fallbacks (was committed
as masked '***' -> nix copy would ssh as user '***' and fail).