feat(V2): builder client centralizzato (solo deribit per ora)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/unit/test_exchanges_builder.py

@@ -0,0 +1,37 @@
+from __future__ import annotations
+
+import pytest
+
+
+@pytest.mark.asyncio
+async def test_build_client_deribit_returns_correct_url(monkeypatch):
+    from tests.unit.test_settings import _minimal_env
+
+    for k, v in _minimal_env().items():
+        monkeypatch.setenv(k, v)
+
+    from cerbero_mcp.settings import Settings
+    from cerbero_mcp.exchanges import build_client
+
+    s = Settings()
+    c_test = await build_client(s, "deribit", "testnet")
+    c_live = await build_client(s, "deribit", "mainnet")
+
+    # DeribitClient espone base_url come property derivata da self.testnet
+    assert "test" in c_test.base_url.lower()
+    assert "test" not in c_live.base_url.lower()
+
+
+@pytest.mark.asyncio
+async def test_build_client_unknown_exchange_raises(monkeypatch):
+    from tests.unit.test_settings import _minimal_env
+
+    for k, v in _minimal_env().items():
+        monkeypatch.setenv(k, v)
+
+    from cerbero_mcp.settings import Settings
+    from cerbero_mcp.exchanges import build_client
+
+    s = Settings()
+    with pytest.raises(ValueError):
+        await build_client(s, "ftx", "testnet")