fix(federation): sync remote node status on list and detect deleted provider shares

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

go-backend/internal/http/handler/handler.go

@@ -321,6 +321,9 @@ func (h *Handler) nodeList(w http.ResponseWriter, r *http.Request) {
 		response.WriteJSON(w, response.Err(-2, err.Error()))
 		return
 	}
+
+	h.syncRemoteNodeStatuses(items)
+
 	response.WriteJSON(w, response.OK(items))
 }