Add the missing Docker events watcher

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docker.go

@@ -170,6 +170,39 @@ func (m *DockerManager) Run(ctx context.Context) {
 	}
 }
 
+// watchEvents listens to container events (start, stop, removal…) so that a
+// new container is followed right away instead of at the next periodic sync.
+func (m *DockerManager) watchEvents(ctx context.Context) {
+	filters := url.QueryEscape(`{"type":["container"]}`)
+	for {
+		resp, err := m.get(ctx, "/events?filters="+filters)
+		if err != nil {
+			if ctx.Err() != nil {
+				return
+			}
+			m.setError(err)
+			sleepCtx(ctx, 5*time.Second)
+			continue
+		}
+		dec := json.NewDecoder(resp.Body)
+		for {
+			var ev struct{ Action string }
+			if err := dec.Decode(&ev); err != nil {
+				break
+			}
+			switch ev.Action {
+			case "create", "start", "die", "destroy", "rename":
+				m.requestSync()
+			}
+		}
+		resp.Body.Close()
+		if ctx.Err() != nil {
+			return
+		}
+		sleepCtx(ctx, time.Second) // stream cut (proxy timeout, Docker restart): reconnect
+	}
+}
+
 func (m *DockerManager) requestSync() {
 	select {
 	case m.syncCh <- struct{}{}: