refactor(V2): bybit client da pybit a httpx puro (parità V1)

tests/unit/exchanges/bybit/conftest.py

@@ -1,21 +1,18 @@
 from __future__ import annotations
 
-from unittest.mock import MagicMock
-
 import pytest
 from cerbero_mcp.exchanges.bybit.client import BybitClient
 
 
 @pytest.fixture
-def mock_http():
-    return MagicMock(name="pybit_HTTP")
+def client():
+    """BybitClient con base_url testnet e AsyncClient interno.
 
-
-@pytest.fixture
-def client(mock_http):
+    pytest-httpx intercetta le chiamate dell'AsyncClient httpx creato dal
+    costruttore (auto-mock), quindi non serve injection esplicita.
+    """
     return BybitClient(
         api_key="test_key",
         api_secret="test_secret",
         testnet=True,
-        http=mock_http,
     )