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/common/tests/test_http.py

@@ -0,0 +1,73 @@
+from __future__ import annotations
+
+import asyncio
+
+import httpx
+import pytest
+
+from mcp_common.http import async_client, call_with_retry
+
+
+def test_async_client_uses_retry_transport():
+    c = async_client(retries=5)
+    assert isinstance(c._transport, httpx.AsyncHTTPTransport)
+    # internal _retries on transport
+    assert c._transport._pool._retries == 5
+
+
+@pytest.mark.asyncio
+async def test_call_with_retry_succeeds_first_try():
+    calls = 0
+
+    async def fn():
+        nonlocal calls
+        calls += 1
+        return "ok"
+
+    result = await call_with_retry(fn)
+    assert result == "ok"
+    assert calls == 1
+
+
+@pytest.mark.asyncio
+async def test_call_with_retry_recovers_after_transient(monkeypatch):
+    monkeypatch.setattr(asyncio, "sleep", asyncio.coroutine(lambda *_: None) if False else _no_sleep)
+    calls = 0
+
+    async def fn():
+        nonlocal calls
+        calls += 1
+        if calls < 3:
+            raise httpx.ConnectError("boom")
+        return "ok"
+
+    result = await call_with_retry(fn, max_attempts=5, base_delay=0.0)
+    assert result == "ok"
+    assert calls == 3
+
+
+async def _no_sleep(_):
+    return None
+
+
+@pytest.mark.asyncio
+async def test_call_with_retry_gives_up_after_max():
+    calls = 0
+
+    async def fn():
+        nonlocal calls
+        calls += 1
+        raise httpx.TimeoutException("slow")
+
+    with pytest.raises(httpx.TimeoutException):
+        await call_with_retry(fn, max_attempts=3, base_delay=0.0)
+    assert calls == 3
+
+
+@pytest.mark.asyncio
+async def test_call_with_retry_does_not_catch_unexpected():
+    async def fn():
+        raise ValueError("not transient")
+
+    with pytest.raises(ValueError):
+        await call_with_retry(fn, max_attempts=5, base_delay=0.0)