feat(scheduling): multi-node service placement + remote lifecycle (#54)

* feat(scheduling): multi-node service placement + remote container lifecycle

services.node_id pins a service to a node agent: explicit id, "auto"
(least-loaded online node), or "local"/empty for the local Docker host.

- DeploymentEngine gains a NodeRunner seam; ReconcileService routes
  pinned services to the agent's command queue (create_container with
  image/env/command/ports/volumes/labels/resource limits), tracked in
  container_instances with deterministic per-replica ids.
- Stop/start/restart/delete fan out to the pinned node — no more leaked
  remote containers on service delete.
- Agent create_container is idempotent (rm -f first) and honors restart
  policy, labels, memory/cpus, published+ephemeral ports, volumes, env.
- GET /nodes/options exposes id/name/status to authed users; full agent
  management stays admin-only.
- CLI services create/update --node, MCP node_id docs, OpenAPI
  node_id/node_name + /nodes/options, service-detail Placement section.

Ceilings: remote nodes run registry-pulled images only — git builds,
Traefik domains, and remote sleep detection stay local until
build-on-node and per-node ingress land.

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

* feat(scheduling): node cordon/drain + schedulable gate

- node_agents.schedulable column; "auto" placement and explicit pins skip
  cordoned nodes; already-pinned services keep running (reconcile is
  unaffected — cordon is not eviction).
- POST /agents/:id/cordon|uncordon|drain (admin). Drain cordons, removes
  every service container via the agent queue, and clears the services'
  pins so they redeploy on the local host. Requires the node online —
  an offline node can't acknowledge removals.
- CLI nodes cordon|uncordon|drain (drain confirm-gated), MCP
  containr_nodes_cordon|uncordon|drain, OpenAPI paths + schedulable
  field, node-detail page cordon badge + drain/cordon controls.
- Fix: re-registering an agent no longer resets auto_prune.

Generated with [Devin](https://devin.ai)

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

* feat(scheduling): remote registry pulls + post-run health check

- Dispatch payload carries the project owner's registry credentials for
  the image host; the agent docker-logins for the pull and logs out
  after, so private images deploy to remote nodes.
- Completed command payloads get their registry password scrubbed —
  secrets don't linger in agent_commands rows.
- Agent verifies the container is still running ~1.5s after docker run;
  crash-loops now fail the deployment with the container's last log
  lines instead of reporting "running" optimistically.

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

---------

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

app/backend/internal/deployment/engine.go

@@ -11,10 +11,24 @@ import (
 	"containr/internal/types"
 )
 
+// NodeRunner deploys a service's containers onto a remote node agent.
+// Wired at boot; nil means every service runs on the local Docker host.
+type NodeRunner interface {
+	// ReconcileOnNode brings the node's containers in line with the spec and
+	// returns the resulting runtime state.
+	ReconcileOnNode(ctx context.Context, spec RuntimeSpec) (*RuntimeState, error)
+	// ControlService fans a lifecycle action ("start"|"stop"|"restart"|"remove")
+	// out to every replica of the service on the agent.
+	ControlService(ctx context.Context, serviceID, agentID, action string) error
+	// RemoveService tears down every replica of the service on the agent.
+	RemoveService(ctx context.Context, serviceID, agentID string) error
+}
+
 type DeploymentEngine struct {
 	buildManager  *build.BuildManager
 	dockerClient  *docker.Client
 	scheduler     *Scheduler
+	nodeRunner    NodeRunner
 	deployments   map[string]*Deployment
 	deploymentLog chan *DeploymentEvent
 }
@@ -67,6 +81,10 @@ type ServiceConfig struct {
 	// PublishedPort is the host port bound by the previous deployment; replica 0
 	// reuses it so public URLs survive restarts. 0 = pick ephemeral.
 	PublishedPort int32 `json:"published_port,omitempty"`
+	// NodeID pins the service to a registered node agent; "" = local Docker
+	// host. Remote placement requires a registry-pullable image — builds stay
+	// on the local host (build-on-node is not yet supported).
+	NodeID string `json:"node_id,omitempty"`
 }
 
 type PortMapping struct {
@@ -177,6 +195,11 @@ func (de *DeploymentEngine) DockerClient() *docker.Client {
 	return de.dockerClient
 }
 
+// SetNodeRunner wires remote-node dispatch for services pinned to an agent.
+func (de *DeploymentEngine) SetNodeRunner(r NodeRunner) {
+	de.nodeRunner = r
+}
+
 func NewDeploymentEngine(buildManager *build.BuildManager, dockerClient *docker.Client) *DeploymentEngine {
 	return &DeploymentEngine{
 		buildManager:  buildManager,
@@ -352,6 +375,7 @@ func (de *DeploymentEngine) deployService(ctx context.Context, deployment *Deplo
 		Maintenance:    cfg.Maintenance,
 		MaintenanceURL: cfg.MaintenanceURL,
 		BasicAuthUsers: cfg.BasicAuthUsers,
+		NodeID:         cfg.NodeID,
 	}
 	for _, pm := range cfg.PortMappings {
 		if spec.Port == 0 {