[TorecLuik]

Summary

• validate the exact backup directory path inside biomeroworker during dry runs
• create and remove only probe-created path components, catching missing mounts and permissions before OMERO discovery
• report the validated backup path in the dry-run result

Verification

• 235 passed, 4 skipped
• compileall and git diff --check pass

Tests are proposed separately against the test-suite branch.