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>

tests/Explorer.Domain.Tests/DomainTests.cs

@@ -43,6 +43,9 @@ public class PathRulesTests
         Assert.Equal(@"Windows\System32", PathRules.MakeRelative(@"C:\", @"C:\Windows\System32"));
         Assert.Equal(@"C:\Windows", PathRules.Parent(@"C:\Windows\System32"));
         Assert.Equal(@"C:\", PathRules.Parent(@"C:\Windows"));
+        Assert.Equal(@"pack.zip\docs", PathRules.RelativeParent(@"pack.zip\docs\a.txt"));
+        Assert.Equal("pack.zip", PathRules.RelativeParent(@"pack.zip\docs"));
+        Assert.Equal("", PathRules.RelativeParent("pack.zip"));
     }
 
     [Fact]
@@ -62,6 +65,31 @@ public class PathRulesTests
     }
 }
 
+public class ArchiveFormatsTests
+{
+    [Fact]
+    public void Detects_common_archive_extensions()
+    {
+        Assert.True(ArchiveFormats.IsArchive("pack.zip"));
+        Assert.True(ArchiveFormats.IsArchive("film.7z"));
+        Assert.True(ArchiveFormats.IsArchive("backup.rar"));
+        Assert.True(ArchiveFormats.IsArchive("src.tar.gz"));
+        Assert.True(ArchiveFormats.IsZipFamily("photos.cbz"));
+        Assert.False(ArchiveFormats.IsArchive("notes.txt"));
+        Assert.False(ArchiveFormats.IsArchive("report.docx"));
+    }
+
+    [Fact]
+    public void Rejects_unsafe_archive_entry_paths()
+    {
+        Assert.True(ArchiveFormats.TryNormalizeEntryPath("docs/a.txt", out var ok));
+        Assert.Equal(@"docs\a.txt", ok);
+        Assert.False(ArchiveFormats.TryNormalizeEntryPath(@"..\escape.txt", out _));
+        Assert.False(ArchiveFormats.TryNormalizeEntryPath(@"C:\abs.txt", out _));
+        Assert.False(ArchiveFormats.TryNormalizeEntryPath("/", out _));
+    }
+}
+
 public class VolumeIdentityTests
 {
     [Fact]