fix: refresh terminal websocket auth on reconnect

Reuse the existing refresh-token flow before opening terminal websocket connections so reconnects can recover from expired access tokens without requiring a full dashboard reload.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

dashboard/frontend/src/lib/api.js

@@ -54,6 +54,15 @@ async function tryRefresh() {
   return refreshPromise;
 }
 
+export async function getWebSocketToken(forceRefresh = false) {
+  if (!forceRefresh && token) return token;
+  const refreshed = await tryRefresh();
+  if (refreshed && token) return token;
+  setToken("");
+  setRefreshToken("");
+  return "";
+}
+
 async function request(path, opts = {}) {
   const headers = opts.headers || {};
   if (token) headers["Authorization"] = `Bearer ${token}`;