swarm-ui, hive dashboard, agent page: one profile menu with the signed-in user, avatar and authelia links

The swarm UI's user menu moves to @hive/shared and takes the whoami URL and
authelia's URL as props; the swarm UI keeps a thin wrapper, and the hive
dashboard and the per-agent page mount the same component. The dashboard's
nginx vhost proxies /api/whoami to authelia (the agent page is served from
the same vhost), and hive-c0re's state carries authelia_public_url, set from
services.hyperhive.swarm.authelia.url. The agent page shows the menu only
behind the gateway.

frontend/packages/dashboard/src/user-menu.js

@@ -0,0 +1,24 @@
+// Profile menu in the dashboard chrome, at the right of the tab strip: the
+// signed-in user's avatar, name, and links to authelia's settings and
+// sign-out. It is `@hive/shared`'s `UserMenu`, the same component the swarm UI
+// and the per-agent page mount, rendered with Preact like the job-queue
+// graph. `/api/whoami` is proxied to authelia by this dashboard's own nginx
+// vhost, so it needs no CORS; authelia's URL comes from `/api/state`.
+
+import { h, render } from "preact";
+import { UserMenu } from "@hive/shared/user-menu.js";
+import { $ } from "./common.js";
+
+/** (Re)render the menu into `#user-menu`. Safe to call on every state
+ *  refresh: Preact diffs the same component, so an open popover stays open. */
+export function renderUserMenu(state) {
+  const root = $("user-menu");
+  if (!root) return;
+  render(
+    h(UserMenu, {
+      whoamiUrl: "/api/whoami",
+      autheliaUrl: (state && state.authelia_public_url) || null,
+    }),
+    root,
+  );
+}