fix(importer): resolve absolute path leakage and retry path inconsistency

[drondeseries]

This PR fixes path resolution bugs in the importer that caused files to be incorrectly placed in temporary directories and resulted in Arrs being unable to find files.

Key Changes:

• Manual Scan: Fixed host-absolute path leakage in DirectoryScanner.
• Virtual Directory: Hardened CalculateVirtualDirectory to ensure relative paths.
• Retry Logic: Sanitized basePath in service.go to prevent host-absolute path usage during retries.
• Reporting: Improved calculateHistoryStoragePath to ensure Arrs receive correct paths.