Add Git overlay, operation tools, and virtualized preview so large folders stay responsive.

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

src/Explorer.Application/LruCache.cs

@@ -0,0 +1,63 @@
+namespace Explorer.Application;
+
+public sealed class LruCache<TKey, TValue>
+    where TKey : notnull
+{
+    private readonly int _capacity;
+    private readonly Dictionary<TKey, LinkedListNode<(TKey Key, TValue Value)>> _map;
+    private readonly LinkedList<(TKey Key, TValue Value)> _order;
+    private readonly object _gate = new();
+
+    public LruCache(int capacity)
+    {
+        ArgumentOutOfRangeException.ThrowIfLessThan(capacity, 1);
+        _capacity = capacity;
+        _map = new Dictionary<TKey, LinkedListNode<(TKey, TValue)>>(capacity);
+        _order = new LinkedList<(TKey, TValue)>();
+    }
+
+    public int Count
+    {
+        get { lock (_gate) return _map.Count; }
+    }
+
+    public bool TryGet(TKey key, out TValue value)
+    {
+        lock (_gate)
+        {
+            if (_map.TryGetValue(key, out var node))
+            {
+                _order.Remove(node);
+                _order.AddFirst(node);
+                value = node.Value.Value;
+                return true;
+            }
+        }
+
+        value = default!;
+        return false;
+    }
+
+    public void Set(TKey key, TValue value)
+    {
+        lock (_gate)
+        {
+            if (_map.TryGetValue(key, out var existing))
+            {
+                _order.Remove(existing);
+                existing.Value = (key, value);
+                _order.AddFirst(existing);
+                return;
+            }
+
+            var node = _order.AddFirst((key, value));
+            _map[key] = node;
+            while (_map.Count > _capacity)
+            {
+                var last = _order.Last!;
+                _order.RemoveLast();
+                _map.Remove(last.Value.Key);
+            }
+        }
+    }
+}