Add queued FFmpeg conversion and finish splitting the window from the host.

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

tests/Explorer.Application.Tests/FileOperationProfilePlannerTests.cs

@@ -160,6 +160,44 @@ public class FileOperationProfilePlannerTests
         Assert.Contains(plan.Issues, i => i.Message.Contains("7-Zip", StringComparison.OrdinalIgnoreCase));
     }
 
+    [Fact]
+    public void Convert_lists_one_job_per_matching_file()
+    {
+        var fs = Tree()
+            .Dir(@"C:\src")
+            .File(@"C:\src\clip.mov", 10, T0)
+            .File(@"C:\src\notes.txt", 1, T0)
+            .Dir(@"C:\dst");
+
+        var plan = Build(new OperationProfile
+        {
+            Name = "Convert",
+            DestPath = @"C:\dst",
+            DoConvert = true,
+            ConversionKind = ConversionKind.VideoToMp4
+        }, fs, [@"C:\src"]);
+        Assert.True(plan.CanEnqueue);
+        var convert = Assert.Single(plan.Operations);
+        Assert.Equal(TransferOp.Convert, convert.Op);
+        Assert.Equal(@"C:\src\clip.mov", convert.SourcePath);
+        Assert.Equal(@"C:\dst\clip.mp4", convert.DestinationPath);
+        Assert.Contains(plan.ProfilePreview, r => r.Action == "Convert");
+    }
+
+    [Fact]
+    public void Missing_ffmpeg_is_an_error()
+    {
+        var fs = Tree().Dir(@"C:\src").File(@"C:\src\clip.mov", 10, T0).Dir(@"C:\dst");
+        var plan = Build(new OperationProfile
+        {
+            Name = "Convert",
+            DestPath = @"C:\dst",
+            DoConvert = true
+        }, fs, [@"C:\src"], convertAvailable: false);
+        Assert.False(plan.CanEnqueue);
+        Assert.Contains(plan.Issues, i => i.Message.Contains("FFmpeg", StringComparison.OrdinalIgnoreCase));
+    }
+
     private static OperationProfile CopyProfile(string dest = @"C:\dst", bool git = false)
         => new()
         {
@@ -176,6 +214,7 @@ public class FileOperationProfilePlannerTests
         GitStatus? git = null,
         bool gitAvailable = true,
         bool compressAvailable = true,
+        bool convertAvailable = true,
         Func<string, bool>? reachable = null,
         Func<FileSystemItem, bool>? wouldHydrate = null)
         => new FileOperationProfilePlanner(new RenamePlanner()).Build(
@@ -188,7 +227,9 @@ public class FileOperationProfilePlannerTests
             compressAvailable,
             SevenZipLocator.MissingHint,
             pathExists: _ => false,
-            wouldHydrate: wouldHydrate);
+            wouldHydrate: wouldHydrate,
+            convertAvailable: convertAvailable,
+            convertMissingHint: FfmpegLocator.MissingHint);
 
     private static TreeEnumerator Tree() => new();
 }