Manage several servers from one panel: core + nodes

A node is a VPN server without a panel. awg-agent on it dials the panel
(core) over an outbound WSS connection and runs the panel's requests on its
own awg-ctrl, which stays on 127.0.0.1 and is unchanged. No inbound port on
the node, works behind NAT.

- awg-ui/nodes.ts: node registry in ui.db, WSS hub on NODE_PORT with a
  self-signed cert whose SPKI pin goes into the join string, RPC with
  timeouts, health polling, /ui/nodes routes.
- Nodes enroll with a one-time awgjoin:// string (secret stored hashed,
  1 hour) and then authenticate by their own Ed25519 key. The agent checks
  the pin before sending anything and only forwards /health, /api/*, /awg/*.
- server_id 0 is the panel's own awg-ctrl; LOCAL_NODE=off makes the panel
  run without a VPN of its own. The panel picks a server with X-Server-Id,
  API keys use their server_id. sen:// still serves one server.
- UI: a card per server in the server bar, switching remounts the tab,
  «Добавить сервер» gives the join command.
- CLI: agent service, roles from cli.env, join / unjoin commands.
- Release archives include awg-agent.

awg-ui/src/lib/shared.ts

@@ -47,10 +47,32 @@ export interface PageProps {
 export const BRAND_FALLBACK = 'Forgetting';
 export interface Brand { brand: string; channel: string; version: string }
 
-export const TOKEN_KEY = 'awg_token';
-export const THEME_KEY = 'awg_theme';
+export const TOKEN_KEY  = 'awg_token';
+export const THEME_KEY  = 'awg_theme';
+export const SERVER_KEY = 'awg_server';
+
+// Сервер (core или нода) в списке ServerBar: то, что отдаёт GET /ui/nodes.
+export interface NodeInfo {
+    id:        number;
+    name:      string;
+    local:     boolean;        // id 0 — локальный awg-ctrl этой же машины
+    online:    boolean;
+    pending:   boolean;        // нода создана, но ещё ни разу не подключалась
+    last_seen: number | null;
+    health:    { server: string; ip: string; gen: AwgGen; peers: number; awg_up: boolean; module: string; tools: string } | null;
+}
+
+// Выбранный сервер. Вкладки зовут apiFetch без явного id — заголовок X-Server-Id
+// подставляется здесь; App ставит значение до смены key у вкладки, поэтому та
+// перечитывает данные уже с новым сервером.
+let currentServerId: number | null = null;
+export const setServerId = (id: number | null) => { currentServerId = id; };
+export const getServerId = () => currentServerId;
+
 export async function apiFetch(method: string, path: string, token: string, body?: object): Promise<any> {
-    const r = await axios({ method, url: path, headers: { Authorization: `Bearer ${token}` }, data: body });
+    const headers: Record<string, string> = { Authorization: `Bearer ${token}` };
+    if (currentServerId !== null) headers['X-Server-Id'] = String(currentServerId);
+    const r = await axios({ method, url: path, headers, data: body });
     return r.data;
 }