Wire applog-listen@enamel error rail when enamel is built

When enamel app is built: provision its error rail so it pages like the other apps. Steps: (1) create applog-listen@enamel systemd user unit + /home/rob/.config/applog/enamel.env with DATABASE_URL_DIRECT; (2) the daemon registers applog-enamel + aro_joins aro:enamel on startup; (3) verify a test error posts to aro:enamel without origin_aro_not_member. HUB SIDE NEEDS NOTHING — MSG-267 (live v2.42.0) already exempts any applog-* / role=applog identity from aros-prune generically, so applog-enamel is auto-covered the moment it registers. This WI is purely the daemon/ops provisioning reminder (same lane as applog-listen.ts). Origin: Elazar 2026-07-13, 'enamel not built yet but will be'.