feat(nodes): remote ingress via Traefik file provider

Remote replicas publish an ephemeral host port; the agent reports the
assigned binding back in the create_container result and the backend
renders a per-service file-provider config into TRAEFIK_DYNAMIC_DIR
pointing Traefik at the node's mesh IP + port. Routes are rewritten on
every remote reconcile and removed on teardown or local placement.

Also: RetireService retires remote leftovers when a service returns to
local placement; remove_container is idempotent agent-side; tombstoned
replicas skip remove dispatch; the domains-stay-local ceiling is gone.

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

app/backend/sqlc/queries/agents.sql

@@ -110,6 +110,12 @@ RETURNING *;
 UPDATE container_instances SET status = $2, updated_at = NOW()
 WHERE id = $1;
 
+-- name: UpdateContainerPorts :exec
+-- Agent reports the real host bindings after create — persist them with
+-- the status flip so ingress can route to the assigned port.
+UPDATE container_instances SET status = $2, ports = $3, updated_at = NOW()
+WHERE id = $1;
+
 -- name: GetLastAgentCommandByType :one
 SELECT * FROM agent_commands
 WHERE node_agent_id = $1 AND type = $2
@@ -174,7 +180,7 @@ LIMIT 1;
 UPDATE node_agents SET tags = $2::jsonb, updated_at = NOW() WHERE id = $1;
 
 -- name: ListServiceContainers :many
-SELECT id, name, node_agent_id, status FROM container_instances
+SELECT id, name, node_agent_id, status, ports FROM container_instances
 WHERE service_id = $1;
 
 -- name: SetAgentSchedulable :exec
@@ -197,5 +203,9 @@ ON CONFLICT (id) DO UPDATE SET
 -- name: DeleteServiceContainersOnAgent :exec
 DELETE FROM container_instances WHERE node_agent_id = $1 AND service_id = $2;
 
+-- name: ListServiceAgents :many
+-- Distinct agents holding inventory rows for a service.
+SELECT DISTINCT node_agent_id FROM container_instances WHERE service_id = $1;
+
 -- name: ScrubCommandPayload :exec
 UPDATE agent_commands SET payload = $2, updated_at = NOW() WHERE id = $1;