Make meeting lifecycle stateful

MeetingAssistant/Speakers/SpeakerIdentityMergeService.cs

@@ -47,7 +47,8 @@ public sealed class SpeakerIdentityMergeService : ISpeakerIdentityMergeService
             .Include(identity => identity.Aliases)
             .Include(identity => identity.CandidateNames)
             .Include(identity => identity.Snippets)
-            .OrderByDescending(identity => identity.TranscriptionCount)
+            .Include(identity => identity.References)
+            .OrderByDescending(identity => identity.References.Count)
             .ThenBy(identity => identity.Id)
             .ToListAsync(cancellationToken);
 
@@ -107,7 +108,14 @@ public sealed class SpeakerIdentityMergeService : ISpeakerIdentityMergeService
                     continue;
                 }
 
+                var targetName = target.GetDisplayName() ?? $"identity-{target.Id}";
+                var sourceName = source.GetDisplayName() ?? $"identity-{source.Id}";
                 MergeIdentities(target, source);
+                await SpeakerIdentityTranscriptAudit.AppendMergedAsync(
+                    target.References,
+                    targetName,
+                    sourceName,
+                    cancellationToken);
                 context.SpeakerIdentities.Remove(source);
                 identities.Remove(source);
                 mergedPairs++;
@@ -138,7 +146,7 @@ public sealed class SpeakerIdentityMergeService : ISpeakerIdentityMergeService
             candidates.Select(identity => new SpeakerIdentityMatchCandidate(
                     identity.Id,
                     identity.GetDisplayName(),
-                    identity.TranscriptionCount,
+                    identity.ReferenceCount,
                     identity.Snippets
                         .OrderBy(snippet => snippet.CreatedAt)
                         .Select(snippet => snippet.WavBytes)
@@ -166,8 +174,12 @@ public sealed class SpeakerIdentityMergeService : ISpeakerIdentityMergeService
             AddAlias(target, candidate.Name);
         }
 
-        target.TranscriptionCount += source.TranscriptionCount;
         target.UpdatedAt = DateTimeOffset.UtcNow;
+        foreach (var reference in source.References)
+        {
+            SpeakerIdentityReferences.AddIfMissing(target, reference);
+        }
+
         var retainedSnippets = target.Snippets
             .Concat(source.Snippets)
             .OrderBy(snippet => StableSnippetKey(snippet.WavBytes))