Fix calculator instance auth header to X-Hub-Token.

Market info fetch was rejected by instances because it sent the wrong bridge token header; align with hub monitor calls.

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

tests/test_hub_calculator_market_lib.py

@@ -58,6 +58,12 @@ class HubCalculatorMarketLibTests(unittest.TestCase):
         self.assertEqual(fn(1.23456), 1.234)
         self.assertIsNone(fn(0.0001))
 
+    @patch.dict("os.environ", {"HUB_BRIDGE_TOKEN": "test-token"}, clear=False)
+    def test_hub_headers_use_x_hub_token(self):
+        from hub_calculator_market_lib import _hub_headers
+
+        self.assertEqual(_hub_headers(), {"X-Hub-Token": "test-token"})
+
     @patch("hub_calculator_market_lib.fetch_instance_market_sync")
     def test_get_calculator_market_from_instance(self, fetch_mock):
         fetch_mock.return_value = {