made the embedding procedure more robust

app/MindWork AI Studio/Tools/Services/DataSourceEmbeddingModels.cs

@@ -82,6 +82,8 @@ public sealed class DataSourceEmbeddingManifest
 
     public string EmbeddingSignature { get; set; } = string.Empty;
 
+    public string SourceHash { get; set; } = string.Empty;
+
     public int VectorSize { get; set; }
 
     public Dictionary<string, EmbeddedFileRecord> Files { get; init; } = new(StringComparer.OrdinalIgnoreCase);