fix(infra): wait for nlp-service healthy before starting backend

Changes condition: service_started → service_healthy so the backend
container does not start until FastAPI has bound its port and loaded
person names from the database. Eliminates the startup race where a
first NL search would return 503 during nlp-service bootstrap.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -196,7 +196,7 @@ services:
       ocr-service:
         condition: service_started
       nlp-service:
-        condition: service_started
+        condition: service_healthy
     environment:
       SPRING_DATASOURCE_URL: jdbc:postgresql://db:5432/${POSTGRES_DB}
       SPRING_DATASOURCE_USERNAME: ${POSTGRES_USER}