Skip symlink directories to avoid traversal into virtual/mounted filesystems

Detects symlinks via ReparsePoint attribute and skips directory symlinks
during scanning. Prevents traversal into Steam.app recursive bundles,
CloudStorage network mounts, CoreSimulator recursive revlinks, and
similar problematic paths.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: HavenDV

src/cli/Tiktoken.Cli/IO/FileScanner.cs

@@ -113,7 +113,7 @@ public IReadOnlyList<string> Scan(string rootPath)
     /// Length is NOT included because on macOS/Linux it triggers an extra stat() syscall
     /// per entry. We defer the stat call to after gitignore/filter checks pass.
     /// </summary>
-    private readonly record struct DirEntry(string FullPath, bool IsDirectory);
+    private readonly record struct DirEntry(string FullPath, bool IsDirectory, bool IsSymlink);
 
     /// <summary>
     /// Enumerates all entries (files + directories) in a single readdir pass using
@@ -126,7 +126,8 @@ private static FileSystemEnumerable<DirEntry> EnumerateEntries(string dirPath)
             dirPath,
             static (ref FileSystemEntry entry) => new DirEntry(
                 entry.ToFullPath(),
-                entry.IsDirectory),
+                entry.IsDirectory,
+                entry.Attributes.HasFlag(FileAttributes.ReparsePoint)),
             new EnumerationOptions
             {
                 IgnoreInaccessible = true,
@@ -194,6 +195,13 @@ private void ScanDirectory(
             {
                 if (entry.IsDirectory)
                 {
+                    // Skip symlink directories to avoid traversing into virtual/mounted
+                    // filesystems, symlink loops, and paths like Steam.app recursive bundles
+                    if (entry.IsSymlink)
+                    {
+                        continue;
+                    }
+
                     var dirName = Path.GetFileName(entry.FullPath);
 
                     if (!_noDefaultExcludes && DefaultExcludedDirs.Contains(dirName))