feat(mcp-deribit,mcp-bybit): add place_combo_order

Deribit: private/create_combo + place_order sul combo instrument → una
sola crociata di spread invece di N (slippage atteso ridotto su
strutture liquide). ACL core + leverage cap su tutti i leg.

Bybit: place_batch_order su category=option (atomic multi-leg, 1
round-trip API). Reject su category != option (perp/linear non
supportano batch nativo). orderLinkId auto-generato per leg.

Tutti i test: deribit 48/48, bybit 123/123.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

services/mcp-deribit/tests/test_client.py

@@ -221,6 +221,67 @@ async def test_get_dvol(httpx_mock: HTTPXMock, client: DeribitClient):
     assert result["candles"][0]["close"] == 57.0
 
 
+@pytest.mark.asyncio
+async def test_place_combo_order(httpx_mock: HTTPXMock, client: DeribitClient):
+    httpx_mock.add_response(
+        url=re.compile(r"https://test\.deribit\.com/api/v2/public/auth"),
+        json=AUTH_RESP,
+    )
+    httpx_mock.add_response(
+        url=re.compile(r"https://test\.deribit\.com/api/v2/private/create_combo"),
+        json={
+            "result": {
+                "id": "BTC-COMBO-1",
+                "instrument_name": "BTC-COMBO-1",
+                "state": "active",
+            }
+        },
+    )
+    httpx_mock.add_response(
+        url=re.compile(r"https://test\.deribit\.com/api/v2/private/buy"),
+        json={
+            "result": {
+                "order": {"order_id": "ord-1", "order_state": "open"},
+                "trades": [],
+            }
+        },
+    )
+    legs = [
+        {"instrument_name": "BTC-30APR26-75000-C", "direction": "buy", "ratio": 1},
+        {"instrument_name": "BTC-30APR26-80000-C", "direction": "sell", "ratio": 1},
+    ]
+    result = await client.place_combo_order(
+        legs=legs,
+        side="buy",
+        amount=1,
+        type="limit",
+        price=0.05,
+        label="vert-spread",
+    )
+    assert result["combo_instrument"] == "BTC-COMBO-1"
+    assert result["order"]["order_id"] == "ord-1"
+
+
+@pytest.mark.asyncio
+async def test_place_combo_order_create_combo_error(httpx_mock: HTTPXMock, client: DeribitClient):
+    httpx_mock.add_response(
+        url=re.compile(r"https://test\.deribit\.com/api/v2/public/auth"),
+        json=AUTH_RESP,
+    )
+    httpx_mock.add_response(
+        url=re.compile(r"https://test\.deribit\.com/api/v2/private/create_combo"),
+        json={"error": {"code": -32602, "message": "Invalid leg"}},
+    )
+    result = await client.place_combo_order(
+        legs=[{"instrument_name": "BTC-X", "direction": "buy", "ratio": 1}],
+        side="buy",
+        amount=1,
+        type="market",
+    )
+    assert result["state"] == "error"
+    assert "Invalid leg" in str(result.get("error"))
+
+
 @pytest.mark.asyncio
 async def test_cancel_order(httpx_mock: HTTPXMock, client: DeribitClient):
     httpx_mock.add_response(