Add flock-based locking to prevent concurrent service operations

source/agent-remote/ds_install.sh

@@ -45,6 +45,10 @@ export TEMP_DIR="${2:-}"
 export DOCKER_CLI_HINTS=false
 
 SERVICE_DIR="${DROPSHELL_DIR}/services/${SERVICE}"
+
+# -- Acquire exclusive lock (released automatically on exit) --
+_lock_service "${SERVICE_DIR}"
+
 LIVE_CONFIG="${SERVICE_DIR}/config"
 LIVE_TEMPLATE="${SERVICE_DIR}/template"
 STAGING_DIR="${SERVICE_DIR}/_staging"