Track E: recreate, system prune, Hub search, swarm secrets/configs

Investigate Docker/Portainer gaps and ship high-value ops: recreate
container, system prune + builder prune UI, Docker Hub search in
pull modal, Swarm secrets/configs tables. Update roadmap Track E/F.

server/handlers/system.js

@@ -58,6 +58,51 @@ export function registerSystemHandlers(session) {
     return { type: 'systemDf', data, success: true }
   })
 
+  /**
+   * Docker system prune (Portainer-style "clean unused data").
+   * @param {{ volumes?: boolean, all?: boolean }} args
+   */
+  session.respond('systemPrune', async (args = {}) => {
+    const volumes = Boolean(args.volumes)
+    const all = Boolean(args.all)
+    let data = null
+    if (typeof docker.pruneSystem === 'function') {
+      data = await docker.pruneSystem({ volumes, all })
+    } else {
+      // Fallback: dial Engine /system/prune directly
+      data = await new Promise((resolve, reject) => {
+        const qs = new URLSearchParams()
+        if (volumes) qs.set('volumes', '1')
+        if (all) qs.set('all', '1')
+        const path = `/system/prune${qs.toString() ? `?${qs}` : ''}`
+        docker.modem.dial(
+          {
+            path,
+            method: 'POST',
+            statusCodes: {
+              200: true,
+              500: 'server error',
+            },
+          },
+          (err, result) => (err ? reject(err) : resolve(result))
+        )
+      })
+    }
+    logger.info('systemPrune completed', {
+      volumes,
+      all,
+      peerId: session.id?.slice?.(0, 12),
+    })
+    return {
+      success: true,
+      type: 'systemPrune',
+      message: volumes
+        ? 'System pruned (including unused volumes)'
+        : 'System pruned (containers, networks, images; volumes kept)',
+      data,
+    }
+  })
+
   session.respond('getMetrics', async () => {
     return getMetricsSnapshot({ peerCount: peers.size })
   })