Revert fly/start.sh to polling loop — tailscale wait needs v1.96.2+

The Fly container pulls from tailscale/tailscale:stable which is still
v1.94.2. The `tailscale wait` command doesn't exist until v1.96.2.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

fly/start.sh

@@ -8,7 +8,7 @@ set -e
 tailscaled --statedir=/var/lib/tailscale &
 sleep 2
 tailscale up --authkey="${TS_AUTHKEY}" --hostname=flyio-proxy
-tailscale wait --timeout 60s
+until tailscale status > /dev/null 2>&1; do sleep 1; done
 echo "Tailscale connected"
 
 # Ensure fail2ban deny file exists before nginx starts