Scene strip: move top row over the preview column and scale it; remove CRT bezel art and on-air seed

- PreviewPane.xaml: drop the OBS-style border Rectangle/Ellipse over webcam elements
- SceneThumbnailStrip: Viewbox scales the row; height follows width so it fills the preview column; staged+live tile has no border
- MainWindow.xaml: strip moved to column 1 only, leaving the layers cell empty; Margin 8,0 matches the preview
- MainViewModel.Background: stop seeding the CRT scene tiles and the on-air image
- ytLive.csproj: per-build counter (BuildCounter.txt, gitignored) replaces the commit-count stamp

Build stamp now increments on every build.

ViewModels/MainViewModel.Background.cs

@@ -441,7 +441,6 @@ public partial class MainViewModel
             if (background != null)
                 StampDefaultBackgroundAsset(background, scene.Name);
         }
-        SeedSceneThumbnails();
         SeedOnAirImage();
         OnPropertyChanged(nameof(ShowSourcesEmptyHint));
     }
@@ -452,45 +451,14 @@ public partial class MainViewModel
     // renders (each scene's original background seen through a CRT screen). They
     // are seeded into the layout's Asset table once per scene; the preview pane
     // keeps rendering each scene's ORIGINAL background — never these tiles.
-    internal static readonly Dictionary<string, string> SceneThumbnailSeedPaths = new(StringComparer.OrdinalIgnoreCase)
-    {
-        [SceneCatalog.Starting] = @"C:\Users\gramp\Downloads\Gemini_Generated_Image_uvq3i3uvq3i3uvq3.jpg",
-        [SceneCatalog.Live] = @"C:\Users\gramp\Downloads\Gemini_Generated_Image_y27sgqy27sgqy27s.jpg",
-        [SceneCatalog.Brb] = @"C:\Users\gramp\Downloads\Gemini_Generated_Image_lxcq0klxcq0klxcq.jpg",
-        [SceneCatalog.Chat] = @"C:\Users\gramp\Downloads\Gemini_Generated_Image_nqosdenqosdenqos.jpg",
-        [SceneCatalog.Ending] = @"C:\Users\gramp\Downloads\Gemini_Generated_Image_8je5n68je5n68je5.jpg",
-    };
-
-    private void SeedSceneThumbnails()
-    {
-        var imported = false;
-        foreach (var scene in Scenes)
-        {
-            if (!string.IsNullOrWhiteSpace(scene.ThumbnailAssetId)) continue;
-            if (!SceneThumbnailSeedPaths.TryGetValue(scene.Name, out var path)) continue;
-            if (!System.IO.File.Exists(path)) continue;
-            try
-            {
-                // UpsertAsset is SHA256-keyed, so a re-seed never duplicates rows
-                // and returns the same id. Only the Scene mapping is new state.
-                var assetId = AddAsset(System.IO.File.ReadAllBytes(path));
-                if (assetId == null) continue;
-                scene.ThumbnailAssetId = assetId;
-                imported = true;
-            }
-            catch { /* the strip keeps the scene's background-art fallback */ }
-        }
-        if (!imported) return;
-        RefreshSnapshotsAsync();
-        ScheduleSave();
-    }
+    internal static readonly Dictionary<string, string> SceneThumbnailSeedPaths = new(StringComparer.OrdinalIgnoreCase);
 
     // ─── On-air strip tile (creator ruling 2026-10-10) ───
     // A single shared image ("on-air background screen") labels whichever scene is
     // CURRENTLY PREVIEWED in the top bar — it replaces that scene's tile and jumps
     // around as the creator swaps scenes. Stored as an Asset row like any image,
     // tracked by the OnAirImageAssetId setting so the Save pruner keeps it alive.
-    internal static string OnAirSeedPath = @"C:\Users\gramp\Downloads\Gemini_Generated_Image_4zajyl4zajyl4zaj.jpg";
+    internal static string OnAirSeedPath = string.Empty;
 
     private System.Windows.Media.Imaging.BitmapImage? OnAirImage;