feat: Fase 1 – Fondamenta complete (backend FastAPI + auth + permessi)

- docker-compose.yml: PostgreSQL 16, Redis 7, MinIO, Nginx
- backend FastAPI: struttura monorepo, config pydantic-settings
- modelli SQLAlchemy: tutti i modelli (tenants, users, mailboxes, messages, archival, permissions, labels, audit_log)
- migrazione Alembic 0001: schema completo in pure SQL
- auth API: login JWT, refresh token rotation, logout, 2FA TOTP (setup/verify/disable)
- CRUD utenti: lista, crea, modifica, reset password, soft delete
- permessi granulari (Fase 1-A): mailbox_permissions, assegna/revoca/lista
- CRUD tenant: gestione super-admin
- sicurezza: AES-256-GCM cifratura credenziali IMAP/SMTP, bcrypt password
- RLS PostgreSQL: isolamento multi-tenant per request
- seed sviluppo: tenant demo + admin + operator
- test unit: security (bcrypt, JWT, AES), auth_service
- test integration: auth endpoints, users endpoints
- CI GitHub Actions: lint (ruff), test (pytest), build Docker, security scan
- infra: nginx.conf, redis.conf
- Makefile con comandi make dev/test/migrate/seed

Definition of Done:
✅ Login, refresh token e TOTP funzionanti
✅ make dev porta in piedi tutto lo stack locale
✅ CI configurata

backend/app/core/logging.py

@@ -0,0 +1,65 @@
+"""
+Structured logging per PecFlow.
+In produzione (LOG_JSON=true) emette log JSON per aggregatori (Loki, ELK).
+In sviluppo emette log leggibili colorati.
+"""
+
+import logging
+import sys
+from typing import Any
+
+from app.config import get_settings
+
+settings = get_settings()
+
+
+def _build_handler() -> logging.Handler:
+    handler = logging.StreamHandler(sys.stdout)
+
+    if settings.log_json:
+        try:
+            import json
+
+            class JsonFormatter(logging.Formatter):
+                def format(self, record: logging.LogRecord) -> str:
+                    log_entry: dict[str, Any] = {
+                        "timestamp": self.formatTime(record, "%Y-%m-%dT%H:%M:%S"),
+                        "level": record.levelname,
+                        "logger": record.name,
+                        "message": record.getMessage(),
+                    }
+                    if record.exc_info:
+                        log_entry["exception"] = self.formatException(record.exc_info)
+                    return json.dumps(log_entry, ensure_ascii=False)
+
+            handler.setFormatter(JsonFormatter())
+        except Exception:
+            pass
+    else:
+        fmt = "%(asctime)s %(levelname)-8s %(name)s – %(message)s"
+        handler.setFormatter(logging.Formatter(fmt, datefmt="%H:%M:%S"))
+
+    return handler
+
+
+def setup_logging() -> None:
+    """Configura il logging applicativo. Da chiamare all'avvio dell'app."""
+    level = getattr(logging, settings.log_level.upper(), logging.INFO)
+
+    root_logger = logging.getLogger()
+    root_logger.setLevel(level)
+
+    # Rimuovi handler esistenti per evitare duplicati
+    root_logger.handlers.clear()
+    root_logger.addHandler(_build_handler())
+
+    # Riduci verbosità librerie rumorose
+    logging.getLogger("uvicorn.access").setLevel(logging.WARNING)
+    logging.getLogger("sqlalchemy.engine").setLevel(
+        logging.INFO if settings.app_debug else logging.WARNING
+    )
+
+
+def get_logger(name: str) -> logging.Logger:
+    """Restituisce un logger con il nome specificato."""
+    return logging.getLogger(name)