feat(R7): metrics + JSON logs + security headers

docker-compose.yml

@@ -18,6 +18,10 @@ services:
       BOOKISH_AUTH_USERNAME: ${BOOKISH_AUTH_USERNAME:-}
       BOOKISH_AUTH_PASSWORD: ${BOOKISH_AUTH_PASSWORD:-}
       BOOKISH_RATE_LIMIT_UPLOAD: ${BOOKISH_RATE_LIMIT_UPLOAD:-20}
+      # Osservabilità: "json" = logging strutturato (1 riga JSON per log)
+      LOG_FORMAT: ${LOG_FORMAT:-}
+      # Timeout conversioni (s); default 300 — alza per libri lunghi
+      BOOKISH_CONVERSION_TIMEOUT: ${BOOKISH_CONVERSION_TIMEOUT:-300}
       PORT: "5000"
     volumes:
       - bookish-data:/data