Show folder names immediately and refresh stale index sizes without walking the whole drive.

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

tests/Explorer.Application.Tests/FavoriteFoldersTests.cs

@@ -0,0 +1,49 @@
+using Explorer.Application;
+using Explorer.Domain;
+
+namespace Explorer.Application.Tests;
+
+public class FavoriteFoldersTests
+{
+    [Fact]
+    public void Normalize_dedupes_and_skips_virtual_roots()
+    {
+        var normalized = FavoriteFolders.Normalize(
+        [
+            @"D:\Photos\",
+            @"d:\photos",
+            LocationRoots.ThisPc,
+            LocationRoots.Favorites,
+            @"C:\Users\Dominique\Documents"
+        ]);
+        Assert.Equal([@"D:\Photos", @"C:\Users\Dominique\Documents"], normalized);
+    }
+
+    [Fact]
+    public void Contains_is_case_insensitive()
+    {
+        var pinned = FavoriteFolders.Normalize([@"D:\Photos"]);
+        Assert.True(FavoriteFolders.Contains(pinned, @"d:\photos\"));
+        Assert.False(FavoriteFolders.Contains(pinned, @"D:\Other"));
+        Assert.False(FavoriteFolders.Contains(pinned, LocationRoots.Home));
+    }
+
+    [Fact]
+    public void Add_appends_new_folders_up_to_max()
+    {
+        var current = Enumerable.Range(0, FavoriteFolders.MaxCount - 1).Select(i => $@"D:\F{i}");
+        var next = FavoriteFolders.Add(current, [@"D:\New", @"D:\F0", @"E:\TooMany"]);
+        Assert.Equal(FavoriteFolders.MaxCount, next.Count);
+        Assert.Equal(@"D:\New", next[^1]);
+        Assert.DoesNotContain(@"E:\TooMany", next);
+    }
+
+    [Fact]
+    public void Remove_unpins_without_touching_other_entries()
+    {
+        var next = FavoriteFolders.Remove(
+            [@"D:\Photos", @"D:\Music"],
+            [@"d:\photos", LocationRoots.ThisPc]);
+        Assert.Equal([@"D:\Music"], next);
+    }
+}