[GUI] Update library page layout (#690)

* [GUI] Add horizontal game tiles

* [GUI] Update launching elements layout

* [GUI] Change cards format to squares

tests/SharpEmu.Libs.Tests/GUI/LibraryTileCollectionTests.cs

@@ -0,0 +1,52 @@
+// Copyright (C) 2026 SharpEmu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+using SharpEmu.GUI;
+using System.Collections;
+using System.Collections.ObjectModel;
+using System.Collections.Specialized;
+using Xunit;
+
+namespace SharpEmu.Libs.Tests.GUI;
+
+public sealed class LibraryTileCollectionTests
+{
+    [Fact]
+    public void KeepsAddFolderTileAfterVisibleGames()
+    {
+        var games = new ObservableCollection<GameEntry>();
+        var tiles = new LibraryTileCollection(games);
+        var first = CreateGame("First");
+        var second = CreateGame("Second");
+
+        games.Add(first);
+        games.Add(second);
+
+        Assert.Equal(3, tiles.Count);
+        Assert.True(tiles is IList { IsReadOnly: true });
+        Assert.Same(first, tiles[0]);
+        Assert.Same(second, tiles[1]);
+        Assert.Same(AddFolderTile.Instance, tiles[2]);
+    }
+
+    [Fact]
+    public void ForwardsGameChangesAtTheirOriginalIndices()
+    {
+        var games = new ObservableCollection<GameEntry>();
+        var tiles = new LibraryTileCollection(games);
+        NotifyCollectionChangedEventArgs? change = null;
+        tiles.CollectionChanged += (_, args) => change = args;
+
+        var game = CreateGame("Game");
+        games.Add(game);
+
+        Assert.NotNull(change);
+        Assert.Equal(NotifyCollectionChangedAction.Add, change.Action);
+        Assert.Equal(0, change.NewStartingIndex);
+        Assert.Same(game, Assert.Single(change.NewItems!.Cast<GameEntry>()));
+        Assert.Same(AddFolderTile.Instance, tiles[1]);
+    }
+
+    private static GameEntry CreateGame(string name) =>
+        new(name, null, null, $"/games/{name}/eboot.bin", 0, null, null);
+}