Brand logo: one locked image layer per scene above the background, image from App Settings

- Source.IsBrandLogo persisted (additive migration); layer healed on load, removal blocked
- Image stored as an asset; settings keep the asset id and file name
- App Settings: Brand Logo file field with Browse
- Default placement top-left; per-scene eye uses the existing element visibility
Test: BrandLogoTests; layout/background tests pass (34). Not pushed.

Services/LayoutStore.Load.cs

@@ -102,7 +102,7 @@ public partial class LayoutStore : IDisposable
                        ChatShowTimestamps, ChatShowBadges, ChatMemberColor, ChatSuperChatColor,
                        WebUri, MediaPath, MediaIsLooping, MediaVolume, MediaPlaybackState,
                        AlertVideoAssetId, AlertVideoPath, AlertUseDefaultVideo, AlertShowTicker, AlertVideoVolume, SortOrder,
-                       AlertDisplayMethod
+                       AlertDisplayMethod, IsBrandLogo
                 FROM Source ORDER BY SortOrder
                 """;
             using var reader = cmd.ExecuteReader();
@@ -154,6 +154,7 @@ public partial class LayoutStore : IDisposable
                     AlertShowTicker = reader.IsDBNull(33) ? true : reader.GetInt32(33) != 0,
                     AlertVideoVolume = reader.IsDBNull(34) ? 1.0 : reader.GetDouble(34),
                     AlertDisplayMethod = reader.IsDBNull(36) ? AlertDisplayMethod.TickerScroll : (AlertDisplayMethod)reader.GetInt32(36),
+                    IsBrandLogo = reader.GetInt32(reader.GetOrdinal("IsBrandLogo")) != 0,
                 };
                 if (!sourcesByScene.TryGetValue(sceneId, out var list))
                     sourcesByScene[sceneId] = list = new List<(Source, int)>();

Services/LayoutStore.Migrations.cs

@@ -199,6 +199,13 @@ public partial class LayoutStore : IDisposable
             cmd.ExecuteNonQuery();
         }
 
+        if (!columns.Contains("IsBrandLogo"))
+        {
+            using var cmd = _connection.CreateCommand();
+            cmd.CommandText = "ALTER TABLE Source ADD COLUMN IsBrandLogo INTEGER NOT NULL DEFAULT 0;";
+            cmd.ExecuteNonQuery();
+        }
+
         if (!columns.Contains("CaptureKey"))
         {
             using var cmd = _connection.CreateCommand();

Services/LayoutStore.Save.cs

@@ -92,7 +92,7 @@ public partial class LayoutStore : IDisposable
                                     ChatShowTimestamps, ChatShowBadges, ChatMemberColor, ChatSuperChatColor,
                                     WebUri, MediaPath, MediaIsLooping, MediaVolume, MediaPlaybackState,
                                     AlertVideoAssetId, AlertVideoPath, AlertUseDefaultVideo, AlertShowTicker, AlertVideoVolume,
-                                    AlertDisplayMethod)
+                                    AlertDisplayMethod, IsBrandLogo)
                 VALUES ($id, $sceneId, $assetId, $type, $name, $isEnabled,
                         $x, $y, $w, $h, $opacity, $monitor,
                         $clip, $mirrored, $isBackground, $captureKey, $showDesktop, $sort,
@@ -100,7 +100,7 @@ public partial class LayoutStore : IDisposable
                         $chatTimestamps, $chatBadges, $chatMemberColor, $chatSuperChatColor,
                         $webUri, $mediaPath, $mediaIsLooping, $mediaVolume, $mediaPlaybackState,
                         $alertVideoAssetId, $alertVideoPath, $alertUseDefaultVideo, $alertShowTicker, $alertVideoVolume,
-                        $alertDisplayMethod)
+                        $alertDisplayMethod, $isBrandLogo)
                 """;
             cmd.Transaction = tx;
             var idP = cmd.Parameters.Add("$id", SqliteType.Text);
@@ -140,6 +140,7 @@ public partial class LayoutStore : IDisposable
             var alertShowTickerP = cmd.Parameters.Add("$alertShowTicker", SqliteType.Integer);
             var alertVideoVolumeP = cmd.Parameters.Add("$alertVideoVolume", SqliteType.Real);
             var alertDisplayMethodP = cmd.Parameters.Add("$alertDisplayMethod", SqliteType.Integer);
+            var isBrandLogoP = cmd.Parameters.Add("$isBrandLogo", SqliteType.Integer);
 
             // Source and WebcamSceneConfig share ONE z-order space per scene:
             // each element gets its index within scene.Elements regardless of
@@ -188,6 +189,7 @@ public partial class LayoutStore : IDisposable
                     alertShowTickerP.Value = source.AlertShowTicker ? 1 : 0;
                     alertVideoVolumeP.Value = source.AlertVideoVolume;
                     alertDisplayMethodP.Value = (int)source.AlertDisplayMethod;
+                    isBrandLogoP.Value = source.IsBrandLogo ? 1 : 0;
                     cmd.ExecuteNonQuery();
                 }
             }

Services/LayoutStore.Settings.cs

@@ -348,4 +348,20 @@ public partial class LayoutStore : IDisposable
 
     /// <summary>The stored on-air image's Asset id, or null when never stamped.</summary>
     public string? GetOnAirImageId() => GetSetting(OnAirImageKey);
+
+    private const string BrandLogoAssetKey = "BrandLogoAssetId";
+    private const string BrandLogoNameKey = "BrandLogoFileName";
+
+    public string? GetBrandLogoAssetId() => GetSetting(BrandLogoAssetKey);
+
+    public string? GetBrandLogoFileName() => GetSetting(BrandLogoNameKey);
+
+    /// <summary>Stores the brand logo image as an asset and records its file name for display.</summary>
+    public string SetBrandLogo(byte[] data, string fileName)
+    {
+        var id = UpsertAsset(data, 0, 0);
+        UpsertSetting(BrandLogoAssetKey, id);
+        UpsertSetting(BrandLogoNameKey, fileName);
+        return id;
+    }
 }