Add settings, cloud places, and optional archive-content indexing.

Keep official clients in charge of sync while Explorer can group locations, persist UI prefs, and list zip/rar/7z members without extracting them.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/Explorer.Domain/PathRules.cs

@@ -150,6 +150,18 @@ public static class PathRules
         return idx < 0 ? p : p[(idx + 1)..];
     }
 
+    public static string RelativeParent(string pathRel)
+    {
+        if (string.IsNullOrEmpty(pathRel))
+        {
+            return string.Empty;
+        }
+
+        var n = NormalizeDirectorySeparators(pathRel).TrimEnd('\\');
+        var idx = n.LastIndexOf('\\');
+        return idx < 0 ? string.Empty : n[..idx];
+    }
+
     public static string JoinDisplay(string? root, string pathRel)
     {
         if (string.IsNullOrWhiteSpace(root))