chore(V2): cleanup quality gate

- ruff: contextlib.suppress al posto di try/except/pass (client_registry, test_env_routing)
- rimozione services/ legacy (residuo da git rm)
- fix integration test fixture: rimosso sys.modules.pop che inquinava module references nei test successivi (test_audit, test_client_init_default_http)

254 test passano. Ruff: clean. Mypy: 68 warning preesistenti dal codice V1 migrato (strict=false).

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

tests/unit/common/test_errors.py

@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from cerbero_mcp.common.errors import error_envelope, HTTP_CODE_MAP
+from cerbero_mcp.common.errors import HTTP_CODE_MAP, error_envelope
 
 
 def test_envelope_minimal():

tests/unit/common/test_mcp_bridge.py

@@ -1,8 +1,8 @@
 from __future__ import annotations
 
+from cerbero_mcp.common.mcp_bridge import _derive_input_schemas, mount_mcp_endpoint
 from fastapi import FastAPI
 from fastapi.testclient import TestClient
-from cerbero_mcp.common.mcp_bridge import _derive_input_schemas, mount_mcp_endpoint
 from pydantic import BaseModel
 
 VALID_TOKEN = "t"