Bluegreen kept timing out — the new green machine couldn't reach
"started" within Fly's 5-minute deploy budget. The cold-start sequence
(tailscaled → tailscale up → wait-for-MagicDNS → nginx startup) eats
most of that, leaving no headroom for healthcheck propagation.
For a single-machine proxy, bluegreen offers little benefit anyway:
no warm second instance, so trading 5-10s of downtime for predictable
completion is the right call.
