chore: httpx retry transport + healthcheck stdlib + mypy config

- mcp_common/http.py: nuovo helper async_client() con
  AsyncHTTPTransport(retries=3) per gestire connection error transient
  + call_with_retry() generic async retry decorator. Sostituite 25
  occorrenze httpx.AsyncClient(...) in deribit/hyperliquid/sentiment/
  macro client. 5 nuovi test.

- Dockerfile healthcheck: passato da python+httpx subprocess a
  stdlib urllib.request.urlopen() su tutti i 6 servizi MCP. Zero
  dipendenze esterne nel runtime check, timeout esplicito 3s, image
  leggermente più snella.

- pyproject.toml: aggiunto [tool.mypy] python_version=3.13 con
  mypy_path multi-package + override ignore_missing_imports per i
  vendor SDK (pybit, alpaca, hyperliquid, pythonjsonlogger). mypy 1.20
  in dev deps; ruff pinned 0.5.x. mcp_common passa mypy clean; 44
  errori tipo pre-esistenti nei servizi affiorati ma non bloccanti —
  fix da pianificare separatamente.

- 455 test verdi.

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

services/mcp-deribit/src/mcp_deribit/client.py

@@ -8,6 +8,7 @@ import httpx
 from mcp_common import indicators as ind
 from mcp_common import microstructure as micro
 from mcp_common import options as opt
+from mcp_common.http import async_client
 
 BASE_LIVE = "https://www.deribit.com/api/v2"
 BASE_TESTNET = "https://test.deribit.com/api/v2"
@@ -43,7 +44,7 @@ class DeribitClient:
             "client_id": self.client_id,
             "client_secret": self.client_secret,
         }
-        async with httpx.AsyncClient(timeout=15.0) as http:
+        async with async_client(timeout=15.0) as http:
             resp = await http.get(url, params=params)
             data = resp.json()
         result = data["result"]
@@ -67,7 +68,7 @@ class DeribitClient:
         if is_private and self._token:
             headers["Authorization"] = f"Bearer {self._token}"
 
-        async with httpx.AsyncClient(timeout=15.0) as http:
+        async with async_client(timeout=15.0) as http:
             resp = await http.get(url, params=request_params, headers=headers)
             data = resp.json()