Added file patterns and exclusions to folder data sources (#1057)

Co-authored-by: Thorsten Sommer <SommerEngineering@users.noreply.github.com>

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

@@ -1,18 +1,21 @@
 namespace AIStudio.Tools.Services;
 
 /// <summary>
-/// The embedding settings an indexing run of a data source works for.
+/// What an indexing run of a data source works for: its embedding settings and the documents it selects.
 /// </summary>
 /// <remarks>
-/// Deliberately nothing but the embedding signature, which decides when a stored index is thrown
-/// away. A run counts as outdated exactly when the next run would throw its work away, and a list of
-/// fields of its own would have to be kept in step with that signature by hand.
+/// A run counts as outdated when the next run would throw its work away, or when it works with
+/// documents which no longer belong to the data source, or misses the ones which now do. Both parts
+/// are descriptions which exist anyway, so no list of fields has to be kept in step with them by
+/// hand: the embedding signature decides when a stored index is thrown away, and the selection
+/// signature is what the selection of a folder tells about itself.
 /// </remarks>
 /// <param name="EmbeddingSignature">The embedding signature of the run, cf. DataSourceEmbeddingService.BuildEmbeddingSignature.</param>
-internal sealed record DataSourceRunSignature(string EmbeddingSignature)
+/// <param name="SelectionSignature">Which documents the run works with, cf. DataSourceEmbeddingService.BuildSelectionSignature.</param>
+internal sealed record DataSourceRunSignature(string EmbeddingSignature, string SelectionSignature)
 {
     /// <summary>
     /// No run would start: the data source or its embedding provider is gone, or that provider may not read it.
     /// </summary>
-    public static readonly DataSourceRunSignature NONE = new(string.Empty);
+    public static readonly DataSourceRunSignature NONE = new(string.Empty, string.Empty);
 }