_TUNNEL_NAME was "tunnel", but the deployment is named castle-tunnel, so
unit_name() produced castle-tunnel.service — a unit that doesn't exist (the
real one is castle-castle-tunnel.service). The is-active check never matched,
so deploy printed "Tunnel not running" and skipped the ingress reload. New
public: true services then 404'd until a manual tunnel restart.
Set _TUNNEL_NAME = "castle-tunnel" to match the deployment name, mirroring
_GATEWAY_NAME. Deploy now restarts cloudflared on ingress changes.