Hide zero USDT in options balance labels and add swap/transfer all buttons.

Skip 0 balances in header display; fill max funding/trading amount on 全部兑换/全部划转.

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

tests/test_instance_header_stats_lib.py

@@ -35,6 +35,7 @@ class TestHeaderStatsLib(unittest.TestCase):
 
     def test_options_funding_label(self):
         self.assertEqual(options_funding_label(1.5, 10), "1.50 USDC · 10.00 USDT")
+        self.assertEqual(options_funding_label(10.19, 0), "10.19 USDC")
         self.assertEqual(options_funding_label(None, 10), "10.00 USDT")
         self.assertEqual(options_funding_label(None, None), "—")