Add OKX-style funds bar with USDT/USDC convert and transfer.

SIM uses multi-wallet balances; LIVE hits OKX asset/account APIs and spot USDC-USDT swap. Funds strip hides sim labeling.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/App.tsx

@@ -6,6 +6,7 @@ import {
   getUsername,
   startAuthTokenAutoRefresh,
 } from "./api/client";
+import FundsBar from "./components/FundsBar";
 import LoginPage from "./pages/Login";
 import PlanPage from "./pages/Plan";
 import TradesPage from "./pages/Trades";
@@ -63,6 +64,7 @@ function Shell({ children }: { children: ReactNode }) {
           </button>
         </div>
       </header>
+      <FundsBar />
       <main className="page">{children}</main>
       <nav className="bottom-nav" aria-label="手机导航">
         {NAV.map((item) => (