[refactor] Add ClassifyEntry method to IFileSystemInspector

[paul-fresquet]

Summary

Refactor IFileSystemInspector to add a centralized ClassifyEntry method that returns the FileSystemEntryKind for any filesystem entry, consolidating all classification logic in one place.

Background

Currently, IFileSystemInspector has separate boolean methods:

• IsHidden()
• IsSystem()
• IsReparsePoint()
• IsOffline()
• IsRecallOnDataAccess()

Classification logic is scattered between FileSystemInspector and InventoryBuilder. This refactoring centralizes the "what type is this entry?" question.

Proposed Interface Changes

public interface IFileSystemInspector
{
    // Existing methods (keep for backward compatibility)
    bool IsHidden(FileSystemInfo fsi, OSPlatforms os);
    bool IsSystem(FileInfo fileInfo);
    bool IsReparsePoint(FileSystemInfo fsi);
    bool Exists(FileInfo fileInfo);
    bool IsOffline(FileInfo fileInfo);
    bool IsRecallOnDataAccess(FileInfo fileInfo);
    
    // New classification method
    FileSystemEntryKind ClassifyEntry(FileSystemInfo fsi);
}

Classification Logic

The ClassifyEntry method should:

1. Check for symlink first (via LinkTarget or ReparsePoint)
2. On Linux/macOS: use POSIX detection for special files
3. Return Directory for DirectoryInfo
4. Return RegularFile for standard FileInfo
5. Return Unknown if classification fails

Acceptance Criteria

• Add ClassifyEntry(FileSystemInfo fsi) to IFileSystemInspector
• Implement in FileSystemInspector with full classification logic
• Integrate POSIX detection (depends on Mono.Posix integration)
• Symlink detection using LinkTarget property (cross-platform)
• Fallback to ReparsePoint check for Windows compatibility
• Unit tests for each entry kind on appropriate platforms
• Existing boolean methods remain functional (no breaking changes)

Dependencies

• Requires: FileSystemEntryKind enum (issue #X)
• Requires: POSIX detection via Mono.Posix (issue [feature] Detect POSIX special files using Mono.Posix.NETStandard #259)

Technical Notes

Example implementation structure:

public FileSystemEntryKind ClassifyEntry(FileSystemInfo fsi)
{
    // 1. Symlink check (cross-platform)
    if (fsi.LinkTarget != null || IsReparsePoint(fsi))
        return FileSystemEntryKind.Symlink;
    
    // 2. POSIX special files (Linux/macOS only)
    if (OperatingSystem.IsLinux() || OperatingSystem.IsMacOS())
    {
        var posixKind = ClassifyPosixEntry(fsi.FullName);
        if (posixKind != FileSystemEntryKind.Unknown)
            return posixKind;
    }
    
    // 3. Standard types
    return fsi switch
    {
        DirectoryInfo => FileSystemEntryKind.Directory,
        FileInfo => FileSystemEntryKind.RegularFile,
        _ => FileSystemEntryKind.Unknown
    };
}

Priority

Important — Core architectural improvement for classification system.