Improve file operations, layout memory, and drive status.

Add a sequential file-operations queue with pause, reorder, and optional auto-clear; persist window size and tree width; show free space; and clear leftover indexing status.

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

tests/Explorer.Application.Tests/BrowseServiceTests.cs

@@ -30,6 +30,8 @@ public class BrowseServiceTests
         var listing = await browse.ListThisPcAsync();
         var item = Assert.Single(listing.Items);
         Assert.Equal(1_073_741_824, item.SizeBytes);
+        Assert.Equal(250_000_000, item.FreeSpaceBytes);
+        Assert.Equal(1_000_000_000, item.CapacityBytes);
         Assert.True(item.IsDirectory);
     }
 
@@ -65,6 +67,7 @@ public class BrowseServiceTests
         var listing = await browse.ListAsync(@"C:\");
         var movies = Assert.Single(listing.Items, i => i.Name == "Movies");
         Assert.Equal(200, movies.SizeBytes);
+        Assert.Equal(250_000_000, movies.FreeSpaceBytes);
         var loose = Assert.Single(listing.Items, i => i.Name == "loose.txt");
         Assert.Equal(10, loose.SizeBytes);
     }
@@ -83,7 +86,9 @@ public class BrowseServiceTests
                     Kind = SourceKind.NtfsLocal,
                     RootPath = root,
                     DisplayName = display,
-                    VolumeSerial = 1
+                    VolumeSerial = 1,
+                    CapacityBytes = 1_000_000_000,
+                    FreeBytes = 250_000_000
                 }
             ]
         };
@@ -128,6 +133,11 @@ file sealed class BrowseVolumes : IVolumeService
         => Online.FirstOrDefault(v => path.StartsWith(v.RootPath.TrimEnd('\\'), StringComparison.OrdinalIgnoreCase));
     public bool IsPathReachable(string path)
         => Online.Any(v => path.StartsWith(v.RootPath.TrimEnd('\\'), StringComparison.OrdinalIgnoreCase));
+    public VolumeSpace GetSpace(string path)
+    {
+        var fp = Probe(path);
+        return new VolumeSpace(fp?.CapacityBytes, fp?.FreeBytes);
+    }
 }
 
 file sealed class BrowseEnv : IAppEnvironment