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.Application.Tests/UiPreferencesStoreTests.cs

@@ -0,0 +1,69 @@
+using Explorer.Application;
+using Explorer.Domain.Abstractions;
+
+namespace Explorer.Application.Tests;
+
+public class UiPreferencesStoreTests
+{
+    [Fact]
+    public void Parse_reads_theme_and_independent_group_flags()
+    {
+        var prefs = UiPreferencesStore.Parse(
+        [
+            "theme=Light",
+            "group-network=true",
+            "group-cloud=false",
+            "index-archives=true"
+        ]);
+        Assert.Equal("Light", prefs.Theme);
+        Assert.True(prefs.GroupNetworkPlaces);
+        Assert.False(prefs.GroupCloudPlaces);
+        Assert.True(prefs.IndexArchiveContents);
+    }
+
+    [Fact]
+    public void Parse_defaults_missing_keys()
+    {
+        var prefs = UiPreferencesStore.Parse(["theme=dark"]);
+        Assert.Equal("Dark", prefs.Theme);
+        Assert.False(prefs.GroupNetworkPlaces);
+        Assert.False(prefs.GroupCloudPlaces);
+        Assert.False(prefs.IndexArchiveContents);
+    }
+
+    [Fact]
+    public void Load_and_save_roundtrip()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "ew-ui-prefs", Guid.NewGuid().ToString("N"));
+        try
+        {
+            var store = new UiPreferencesStore(new PrefsEnv(dir));
+            store.Save(new UiPreferences("Light", true, false, true));
+            var loaded = store.Load();
+            Assert.Equal("Light", loaded.Theme);
+            Assert.True(loaded.GroupNetworkPlaces);
+            Assert.False(loaded.GroupCloudPlaces);
+            Assert.True(loaded.IndexArchiveContents);
+        }
+        finally
+        {
+            try { Directory.Delete(dir, true); } catch { /* ignore */ }
+        }
+    }
+}
+
+file sealed class PrefsEnv : IAppEnvironment
+{
+    public PrefsEnv(string dir)
+    {
+        DataDirectory = dir;
+        Directory.CreateDirectory(dir);
+        DatabasePath = Path.Combine(dir, "index.db");
+        LogDirectory = Path.Combine(dir, "logs");
+        Directory.CreateDirectory(LogDirectory);
+    }
+
+    public string DataDirectory { get; }
+    public string DatabasePath { get; }
+    public string LogDirectory { get; }
+}