GHSA-g39v-cvjh-8fpf: Home Assistant MCP Server: YAML config backups written under www/ are served unauthenticated at /local/

When ENABLE_YAML_CONFIG_EDITING=true, every ha_config_set_yaml call backs up the pre-edit file to <config>/www/yaml_backups/, which Home Assistant serves at /local/ with no authentication. Anyone who can reach the HA web interface can download the most recent pre-edit configuration.yaml (or other YAML file) — typically containing plaintext MQTT passwords, REST credentials, webhook IDs, geofence coordinates, and shell_command definitions — with zero credentials.