[GUI] Update library page layout (#690)

* [GUI] Add horizontal game tiles

* [GUI] Update launching elements layout

* [GUI] Change cards format to squares

src/SharpEmu.GUI/LibraryTileCollection.cs

@@ -0,0 +1,103 @@
+// Copyright (C) 2026 SharpEmu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+using System.Collections;
+using System.Collections.ObjectModel;
+using System.Collections.Specialized;
+
+namespace SharpEmu.GUI;
+
+/// <summary>
+/// Read-only view of the visible games with one persistent action tile at
+/// the end. Game collection changes keep their original indices, so Avalonia
+/// can update and virtualize the rail without rebuilding every item.
+/// </summary>
+public sealed class LibraryTileCollection : IReadOnlyList<LibraryTile>, IList, INotifyCollectionChanged
+{
+    private readonly ObservableCollection<GameEntry> _games;
+
+    public LibraryTileCollection(ObservableCollection<GameEntry> games)
+    {
+        _games = games;
+        _games.CollectionChanged += OnGamesCollectionChanged;
+    }
+
+    public event NotifyCollectionChangedEventHandler? CollectionChanged;
+
+    public int Count => _games.Count + 1;
+
+    bool IList.IsFixedSize => false;
+
+    bool IList.IsReadOnly => true;
+
+    bool ICollection.IsSynchronized => false;
+
+    object ICollection.SyncRoot => this;
+
+    public LibraryTile this[int index]
+    {
+        get
+        {
+            if ((uint)index < (uint)_games.Count)
+            {
+                return _games[index];
+            }
+
+            if (index == _games.Count)
+            {
+                return AddFolderTile.Instance;
+            }
+
+            throw new ArgumentOutOfRangeException(nameof(index));
+        }
+    }
+
+    object? IList.this[int index]
+    {
+        get => this[index];
+        set => throw new NotSupportedException();
+    }
+
+    public IEnumerator<LibraryTile> GetEnumerator()
+    {
+        foreach (var game in _games)
+        {
+            yield return game;
+        }
+
+        yield return AddFolderTile.Instance;
+    }
+
+    IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+
+    int IList.Add(object? value) => throw new NotSupportedException();
+
+    void IList.Clear() => throw new NotSupportedException();
+
+    bool IList.Contains(object? value) => ((IList)this).IndexOf(value) >= 0;
+
+    int IList.IndexOf(object? value) => value switch
+    {
+        GameEntry game => _games.IndexOf(game),
+        AddFolderTile => _games.Count,
+        _ => -1,
+    };
+
+    void IList.Insert(int index, object? value) => throw new NotSupportedException();
+
+    void IList.Remove(object? value) => throw new NotSupportedException();
+
+    void IList.RemoveAt(int index) => throw new NotSupportedException();
+
+    void ICollection.CopyTo(Array array, int index)
+    {
+        ArgumentNullException.ThrowIfNull(array);
+        foreach (var tile in this)
+        {
+            array.SetValue(tile, index++);
+        }
+    }
+
+    private void OnGamesCollectionChanged(object? sender, NotifyCollectionChangedEventArgs args) =>
+        CollectionChanged?.Invoke(this, args);
+}