storage:report gains a flat dotted key per attachment field (entry-name, host-path, container-path, phases, process-type, subpath, readonly, volume-options, volume-chown) under the --storage-attachment.<index>.<field> shape. Both stdout and JSON pick the keys up through the existing common.ReportSingleApp pipeline. Attachments that reference a missing storage entry emit a warning and are skipped, so the rest of the report still renders. Closes#8710.