Add configurable admin password via environment variable

docker-compose.local.yml

@@ -26,6 +26,8 @@ services:
       - ORCHARD_REDIS_PORT=6379
       # Higher rate limit for local development/testing
       - ORCHARD_LOGIN_RATE_LIMIT=1000/minute
+      # Admin password - set in .env file or environment (see .env.example)
+      - ORCHARD_ADMIN_PASSWORD=${ORCHARD_ADMIN_PASSWORD:-}
     depends_on:
       postgres:
         condition: service_healthy