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

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

tests/Explorer.Application.Tests/CloudProviderTests.cs

@@ -10,6 +10,13 @@ namespace Explorer.Application.Tests;
 
 public class CloudProviderTests
 {
+    [Fact]
+    public async Task Quota_returns_null_when_provider_throws()
+    {
+        var registry = new StorageProviderRegistry([new QuotaThrowingProvider()], NullLogger<StorageProviderRegistry>.Instance);
+        Assert.Null(await registry.TryGetQuotaAsync(@"C:\OneDrive"));
+    }
+
     [Fact]
     public async Task Enrich_passes_through_when_provider_throws()
     {
@@ -246,6 +253,19 @@ file sealed class ThrowingProvider : IStorageProvider
         => throw new InvalidOperationException("quota failed");
 }
 
+file sealed class QuotaThrowingProvider : IStorageProvider
+{
+    public ProviderManifest Manifest { get; } = new("onedrive", "OneDrive", "1", ProviderIsolation.InProcess);
+    public ProviderCapability GetCapabilities() => ProviderCapability.Quota;
+    public bool TryMatchRoot(string path) => path.Contains("OneDrive", StringComparison.OrdinalIgnoreCase);
+    public Task<IReadOnlyList<ProviderItemState>> GetItemStatesAsync(IReadOnlyList<string> paths, CancellationToken cancellationToken = default)
+        => Task.FromResult<IReadOnlyList<ProviderItemState>>([]);
+    public Task<ProviderActionResult> TryInvokeAsync(ProviderActionRequest request, CancellationToken cancellationToken = default)
+        => Task.FromResult(new ProviderActionResult(ProviderActionStatus.Unsupported));
+    public Task<ProviderQuota?> TryGetQuotaAsync(string rootPath, CancellationToken cancellationToken = default)
+        => throw new InvalidOperationException("quota failed");
+}
+
 file sealed class StubProvider : IStorageProvider
 {
     public ProviderManifest Manifest { get; } = new("onedrive", "OneDrive", "1", ProviderIsolation.InProcess);