feat(release): add plain-text Description field plumbed CMS->DTO->release (11.G)

New nullable Description column (max 4000) on ReleaseEntity, rides the Genre write channel through upload + edit; multiline CMS input. Migration authored, not applied.

DeepDrftManager/Components/Pages/Tracks/BatchEdit.razor

@@ -33,6 +33,7 @@
         <AlbumHeaderFields @bind-AlbumName="_albumName"
                            @bind-Artist="_artist"
                            @bind-Genre="_genre"
+                           @bind-Description="_description"
                            @bind-ReleaseDate="_releaseDate"
                            @bind-ReleaseType="_releaseType"
                            Medium="_medium"
@@ -137,6 +138,7 @@
     private string _albumName = string.Empty;
     private string _artist = string.Empty;
     private string _genre = string.Empty;
+    private string _description = string.Empty;
     private string _releaseDate = string.Empty;
     private ReleaseType _releaseType = ReleaseType.Single;
     private ReleaseMedium _medium = ReleaseMedium.Cut;
@@ -211,6 +213,7 @@
         _albumName = albumName;
         _artist = release?.Artist ?? string.Empty;
         _genre = release?.Genre ?? string.Empty;
+        _description = release?.Description ?? string.Empty;
         _releaseDate = release?.ReleaseDate?.ToString("yyyy-MM-dd") ?? string.Empty;
         _releaseType = release?.ReleaseType ?? ReleaseType.Single;
         _medium = release?.Medium ?? ReleaseMedium.Cut;
@@ -382,6 +385,7 @@
             : DateOnly.ParseExact(_releaseDate, "yyyy-MM-dd");
         var album = string.IsNullOrWhiteSpace(_albumName) ? null : _albumName;
         var genre = string.IsNullOrWhiteSpace(_genre) ? null : _genre;
+        var description = string.IsNullOrWhiteSpace(_description) ? null : _description;
 
         // For single-track media (Session/Mix) the track name is derived from the Release Name —
         // no separate Track Name editor is shown. Sync here so changes to the Release Name always
@@ -446,6 +450,7 @@
                             _artist,
                             album,
                             genre,
+                            description,
                             releaseDate,
                             imagePathForUpdate,
                             _releaseType,
@@ -480,6 +485,7 @@
                             _artist,
                             album,
                             genre,
+                            description,
                             string.IsNullOrWhiteSpace(_releaseDate) ? null : _releaseDate,
                             row.WavFile.Name,
                             createdByUserId,
@@ -508,6 +514,7 @@
                                     _artist,
                                     album,
                                     genre,
+                                    description,
                                     releaseDate,
                                     linkPath,
                                     _releaseType,