Add ISO9660 and Joliet extraction tests

[ashishsinghbora]

Problem Statement

Windows installation media depends on correctly reading files from the source ISO.

Incorrect path, filename, offset, or file-size handling can result in incomplete installation media.

Proposed Solution / Enhancement

Add tests for:

• ISO9660 files
• ISO9660 directories
• Nested directories
• Joliet filenames
• Long filenames
• Large files
• File offsets
• File sizes

Verify extracted files against known-good source data using hashes.

Architectural Layer Impacted

ISO9660 / Filesystem Layer

Alternatives Considered

Testing only a small example ISO may not expose filename and directory edge cases.