feat(swarm): autonomous agent containers, Swarm Manager with auto-stop, /nodes UI overhaul

## 1. Fix /nodes Swarm Status Display
- Add SwarmStatusBanner component: clear green/red/loading state
- Shows nodeId, managerAddr, isManager badge
- Error state explains what to check (docker.sock mount)
- Header now shows 'swarm unreachable — check gateway' vs 'active'
- swarmOk now checks nodeId presence, not just data existence

## 2. Autonomous Agent Container
- New docker/Dockerfile.agent — builds Go agent binary from gateway/cmd/agent/
- New gateway/cmd/agent/main.go — standalone HTTP microservice:
  * GET /health — liveness probe with idle time info
  * POST /task — receives task, forwards to Gateway orchestrator
  * GET /info  — agent metadata (id, hostname, gateway url)
  * Idle watchdog: calls /api/swarm/agents/{name}/stop after IdleTimeoutMinutes
  * Connects to Swarm overlay network (goclaw-net) → reaches DB/Gateway by DNS
  * Env: AGENT_ID, GATEWAY_URL, DATABASE_URL, IDLE_TIMEOUT_MINUTES

## 3. Swarm Manager Agent (auto-stop after 15min idle)
- New gateway/internal/api/swarm_manager.go:
  * SwarmManager goroutine checks every 60s
  * Scales idle GoClaw agent services to 0 replicas after 15 min
  * Tracks lastActivity from task UpdatedAt timestamps
- New REST endpoints in gateway:
  * GET  /api/swarm/agents           — list agents with idleMinutes
  * POST /api/swarm/agents/{name}/start — scale up agent
  * POST /api/swarm/agents/{name}/stop  — scale to 0
  * DELETE /api/swarm/services/{id}     — remove service permanently
- SwarmManager started as background goroutine in main.go with context cancel

## 4. Docker Client Enhancements
- Added NetworkAttachment type and Networks field to ServiceSpec
- CreateAgentServiceFull(opts) — supports overlay networks, custom labels
- CreateAgentService() delegates to CreateAgentServiceFull for backward compat
- RemoveService(id) — DELETE /v1.44/services/{id}
- GetServiceLastActivity(id) — finds latest task UpdatedAt for idle detection

## 5. tRPC & Gateway Proxy
- New functions: removeSwarmService, listSwarmAgents, startSwarmAgent, stopSwarmAgent
- SwarmAgentInfo type with idleMinutes, lastActivity, desiredReplicas
- createAgentService now accepts networks[] parameter
- New tRPC endpoints: nodes.removeService, nodes.listAgents, nodes.startAgent, nodes.stopAgent

## 6. Nodes.tsx UI Overhaul
- SwarmStatusBanner component at top — no more silent 'connecting…'
- New 'Agents' tab with AgentManagerRow: idle time, auto-stop warning, start/stop/remove buttons
- IdleColor coding: green < 5m, yellow 5-10m, red 10m+ with countdown to auto-stop
- ServiceRow: added Remove button with confirmation dialog
- RemoveConfirmDialog component
- DeployAgentDialog: added overlay networks field, default env includes GATEWAY_URL
- All queries refetch after agent start/stop/remove

server/gateway-proxy.ts

@@ -703,7 +703,7 @@ export async function setNodeAvailability(nodeId: string, availability: "active"
 
 /** Deploy a new agent as a Swarm service */
 export async function createAgentService(opts: {
-  name: string; image: string; replicas: number; env?: string[]; port?: number;
+  name: string; image: string; replicas: number; env?: string[]; port?: number; networks?: string[];
 }): Promise<{ ok: boolean; serviceId?: string; name?: string } | null> {
   try {
     const res = await fetch(`${GATEWAY_BASE_URL}/api/swarm/services/create`, {
@@ -716,3 +716,61 @@ export async function createAgentService(opts: {
     return res.json();
   } catch { return null; }
 }
+
+/** Remove (stop) a Swarm service by ID or name */
+export async function removeSwarmService(serviceId: string): Promise<boolean> {
+  try {
+    const res = await fetch(`${GATEWAY_BASE_URL}/api/swarm/services/${encodeURIComponent(serviceId)}`, {
+      method: "DELETE",
+      signal: AbortSignal.timeout(10_000),
+    });
+    return res.ok;
+  } catch { return false; }
+}
+
+export interface SwarmAgentInfo {
+  id: string;
+  name: string;
+  image: string;
+  desiredReplicas: number;
+  runningTasks: number;
+  lastActivity: string;
+  idleMinutes: number;
+  isGoClaw: boolean;
+}
+
+/** List all GoClaw agent services with idle time info */
+export async function listSwarmAgents(): Promise<{ agents: SwarmAgentInfo[]; count: number } | null> {
+  try {
+    const res = await fetch(`${GATEWAY_BASE_URL}/api/swarm/agents`, {
+      signal: AbortSignal.timeout(10_000),
+    });
+    if (!res.ok) return null;
+    return res.json();
+  } catch { return null; }
+}
+
+/** Start (scale-up) an agent service */
+export async function startSwarmAgent(name: string, replicas = 1): Promise<boolean> {
+  try {
+    const res = await fetch(`${GATEWAY_BASE_URL}/api/swarm/agents/${encodeURIComponent(name)}/start`, {
+      method: "POST",
+      headers: { "Content-Type": "application/json" },
+      body: JSON.stringify({ replicas }),
+      signal: AbortSignal.timeout(10_000),
+    });
+    return res.ok;
+  } catch { return false; }
+}
+
+/** Stop (scale-to-0) an agent service */
+export async function stopSwarmAgent(name: string): Promise<boolean> {
+  try {
+    const res = await fetch(`${GATEWAY_BASE_URL}/api/swarm/agents/${encodeURIComponent(name)}/stop`, {
+      method: "POST",
+      signal: AbortSignal.timeout(10_000),
+    });
+    return res.ok;
+  } catch { return false; }
+}
+