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/styles/app.css

@@ -80,7 +80,52 @@ input {
 .app-shell {
   min-height: 100vh;
   display: grid;
-  grid-template-rows: auto 1fr;
+  grid-template-rows: auto auto 1fr;
+}
+
+.funds-bar {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 2px 0;
+  padding: 8px 12px;
+  border-bottom: 1px solid var(--line);
+  background: rgba(18, 22, 28, 0.96);
+  overflow-x: auto;
+  -webkit-overflow-scrolling: touch;
+}
+
+.funds-item {
+  flex: 1 1 auto;
+  min-width: 88px;
+  padding: 4px 10px;
+  border-right: 1px solid var(--line);
+}
+
+.funds-item:last-child {
+  border-right: none;
+}
+
+.funds-item--primary .funds-value {
+  color: var(--accent);
+}
+
+.funds-label {
+  font-size: 11px;
+  color: var(--muted);
+  line-height: 1.2;
+  margin-bottom: 2px;
+  white-space: nowrap;
+}
+
+.funds-value {
+  font-size: 13px;
+  font-weight: 600;
+  line-height: 1.25;
+  white-space: nowrap;
+}
+
+.funds-item--pnl .funds-value {
+  font-variant-numeric: tabular-nums;
 }
 
 .topnav {