feat: add local Resemblyzer speaker recognition

MeetingAssistant/Speakers/SpeakerIdentityMerger.cs

@@ -2,10 +2,24 @@ namespace MeetingAssistant.Speakers;
 
 internal static class SpeakerIdentityMerger
 {
+    public static void MergeIntoAndPrune(
+        SpeakerIdentity target,
+        SpeakerIdentity source,
+        int maxSnippets,
+        int maxVoiceVectors,
+        ResemblyzerVoiceVectorOutlierPruner outlierPruner)
+    {
+        outlierPruner.Prune(target);
+        outlierPruner.Prune(source);
+        MergeInto(target, source, maxSnippets, maxVoiceVectors);
+        outlierPruner.Prune(target);
+    }
+
     public static void MergeInto(
         SpeakerIdentity target,
         SpeakerIdentity source,
-        int maxSnippets)
+        int maxSnippets,
+        int maxVoiceVectors = int.MaxValue)
     {
         AddAlias(target, source.CanonicalName);
         foreach (var alias in source.Aliases)
@@ -35,6 +49,26 @@ internal static class SpeakerIdentityMerger
             .ToList();
         target.Snippets.Clear();
         target.Snippets.AddRange(retainedSnippets);
+
+        var retainedVectors = target.VoiceVectors
+            .Concat(source.VoiceVectors)
+            .GroupBy(vector => vector.Fingerprint, StringComparer.Ordinal)
+            .Select(group => group.OrderByDescending(vector => vector.CreatedAt).First())
+            .OrderByDescending(vector => vector.CreatedAt)
+            .ThenBy(vector => vector.Fingerprint, StringComparer.Ordinal)
+            .Take(Math.Max(1, maxVoiceVectors))
+            .Select(vector => new SpeakerVoiceVector
+            {
+                SpeakerIdentity = target,
+                ModelId = vector.ModelId,
+                Dimensions = vector.Dimensions,
+                VectorBytes = vector.VectorBytes.ToArray(),
+                Fingerprint = vector.Fingerprint,
+                CreatedAt = vector.CreatedAt
+            })
+            .ToList();
+        target.VoiceVectors.Clear();
+        target.VoiceVectors.AddRange(retainedVectors);
         target.UpdatedAt = DateTimeOffset.UtcNow;
     }