Hardening round 2: healthcheck, audit anchor, return_4h, exec config, signals

Sei interventi MEDIA priorità sul sistema. 323 test pass, mypy strict
pulito, ruff clean.

1. Docker HEALTHCHECK + cerbero-bite healthcheck:
   - nuovo subcommand che esce 0 se kill_switch=0 e last_health_check
     entro --max-staleness-s (default 600s);
   - HEALTHCHECK direttiva nel Dockerfile (60s interval, 5s timeout,
     start_period 120s, retries 3);
   - healthcheck definition nel docker-compose.yml.

2. Audit hash chain anti-truncation:
   - migration 0002: nuova colonna system_state.last_audit_hash;
   - AuditLog accetta callback on_append, dependencies.py la wire al
     repository.set_last_audit_hash;
   - Orchestrator.boot verifica che il tail file matcha l'anchor
     persistito; mismatch → kill switch CRITICAL.

3. return_4h bootstrap da deribit get_historical:
   - quando dvol_history è vuoto _fetch_return_4h cade su
     deribit.historical_close (1h candle 4h fa);
   - alert LOW se anche il fallback fallisce.

4. execution.environment + execution.eur_to_usd in strategy.yaml:
   - ExecutionConfig promosso a typed schema con i due campi
     consumati al boot;
   - CLI start preferisce i valori da config; CLI flag overridano
     solo quando differenti dai default.

5. Cycle correlation ID:
   - structlog.contextvars.bind_contextvars in run_entry/run_monitor/
     run_health propaga cycle_id e cycle nei log strutturati.

6. SIGTERM/SIGINT clean shutdown:
   - run_forever installa loop.add_signal_handler per SIGTERM e
     SIGINT; il segnale set()ta un asyncio.Event che termina il
     blocco principale, scheduler.shutdown e ctx.aclose finalizzano.

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

docker-compose.yml

@@ -48,6 +48,13 @@ services:
       CERBERO_BITE_MCP_PORTFOLIO_URL: http://mcp-portfolio:9018
     volumes:
       - bite-data:/app/data
+    healthcheck:
+      test:
+        ["CMD", "cerbero-bite", "healthcheck", "--db", "/app/data/state.sqlite"]
+      interval: 60s
+      timeout: 5s
+      retries: 3
+      start_period: 120s
     # Default command runs the engine status check; override with the
     # CLI subcommand of choice (start, ping, dry-run, ...).
     command: ["status"]