lint: ruff clean services/ (autofix + manual + ignore E741)

- 24 autofix safe (SIM105 contextlib.suppress, F401 unused imports,
  I001 import order, B007 unused loop var, F811 redef, F841 unused).
- 15 unsafe-fix (UP038 X|Y in isinstance, SIM108 ternary, ecc.).
- Manual fix: SIM102 nested if in deribit term_structure, E402 imports
  in test_cot.py + sentiment server.py.
- Ignore E741 (variabili 'l' in list comprehensions deribit/client.py
  — stilistico, non bug).

Tests: 478/478 verdi.

services/mcp-sentiment/src/mcp_sentiment/server.py

@@ -9,8 +9,6 @@ from mcp_common.mcp_bridge import mount_mcp_endpoint
 from mcp_common.server import build_app
 from pydantic import BaseModel
 
-logger = logging.getLogger(__name__)
-
 from mcp_sentiment.fetchers import (
     fetch_cointegration_pairs,
     fetch_cross_exchange_funding,
@@ -23,6 +21,8 @@ from mcp_sentiment.fetchers import (
     fetch_world_news,
 )
 
+logger = logging.getLogger(__name__)
+
 # --- Body models ---
 
 class GetCryptoNewsReq(BaseModel):