RFC 0006: Restore extended file attributes in direct-to-filesystem restores

[rmanibus]

Context

RFC 0006 introduces direct-to-filesystem restore, and RFC 0004 defines capture of extended filesystem metadata. We should explicitly track the restore-side work that replays extended file attributes when restoring to a directory.

Parent epic: #104
Related RFCs: RFC 0004, RFC 0006

Scope

• Restore stored xattrs during restore -format dir where supported.
• Preserve graceful fallback behavior on filesystems or platforms that do not support specific attributes.
• Ensure restore ordering and error handling do not leave partially applied metadata in surprising states.
• Add coverage for xattr replay behavior in unit and/or e2e tests where feasible.

Acceptance Criteria

• Direct-to-filesystem restore attempts to replay stored xattrs on supported platforms.
• Unsupported or denied xattr operations surface clear, actionable behavior.
• Existing restore flows remain compatible when metadata is absent.
• Tests cover success and fallback/error paths.