feat(nodes): remote sleep/wake — idle detection + wake-page ingress

Agents report per-container net IO at heartbeat; the sleeper measures
idleness from those counters for remote services, removes replicas via
the agent queue, and repoints the domain route at the backend's new
/internal/wake-page endpoint (replacePath + priority-100 route in the
file provider). First hit serves a reloading page and retriggers the
wake reconcile, which recreates replicas and restores real upstreams.

Manual POST /services/:id/sleep also routes remote; local sleep/wake
flow is unchanged.

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

infra/docker-compose.yml

@@ -103,6 +103,7 @@ services:
       - CONTAINR_AGENT_AUTH_TOKEN=${CONTAINR_AGENT_AUTH_TOKEN:-}
       - CONTAINR_AGENT_AUTH_TOKENS=${CONTAINR_AGENT_AUTH_TOKENS:-}
       - TRAEFIK_DYNAMIC_DIR=/traefik-dynamic
+      - TRAEFIK_BACKEND_URL=http://containr-backend:8080
       - COOKIE_SECURE=${COOKIE_SECURE:-true}
       - TRUSTED_PROXY_CIDR=${TRUSTED_PROXY_CIDR:-172.20.0.0/16}
       - CORS_ORIGINS=${CORS_ORIGINS:-http://localhost,http://localhost:3000}