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

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

src/Explorer.Application/SourceManager.cs

@@ -64,6 +64,10 @@ public sealed class SourceManager
                     await _store.Entries.MarkSourceOnlinePresentAsync(source.Id, cancellationToken).ConfigureAwait(false);
                 }
             }
+            else if (fp.Kind.IsNetwork())
+            {
+                continue;
+            }
             else
             {
                 source = new Source
@@ -302,6 +306,29 @@ public sealed class SourceManager
         return created;
     }
 
+    public async Task<IReadOnlyList<VolumeFingerprint>> ListUntrackedOnlineVolumesAsync(CancellationToken cancellationToken = default)
+    {
+        var known = await _store.Sources.GetAllAsync(cancellationToken).ConfigureAwait(false);
+        var untracked = new List<VolumeFingerprint>();
+        foreach (var fp in _volumes.EnumerateOnlineVolumes())
+        {
+            var match = VolumeIdentityMatcher.Match(fp, known);
+            if (match.Source is not null && !match.Ambiguous)
+            {
+                continue;
+            }
+
+            if (known.Any(s => s.LastRootPath is not null && RootsEqual(s.LastRootPath, fp.RootPath)))
+            {
+                continue;
+            }
+
+            untracked.Add(fp);
+        }
+
+        return untracked;
+    }
+
     private async Task<Source?> FindSourceRootAsync(string path, CancellationToken cancellationToken)
     {
         if (string.IsNullOrWhiteSpace(path) || LocationRoots.IsVirtual(path))