Normalize scalar frontmatter lists

MeetingAssistant/Summary/BoundMeetingProjectResolver.cs

@@ -7,9 +7,7 @@ public sealed record BoundMeetingProject(string Name, string Path);
 
 public sealed class BoundMeetingProjectResolver
 {
-    private static readonly IDeserializer YamlDeserializer = new DeserializerBuilder()
-        .IgnoreUnmatchedProperties()
-        .Build();
+    private static readonly IDeserializer YamlDeserializer = FrontmatterYamlDeserializer.Create();
 
     private readonly MeetingAssistantOptions options;
 

MeetingAssistant/Summary/MeetingSummaryFrontmatterFactory.cs

@@ -5,9 +5,7 @@ namespace MeetingAssistant.Summary;
 
 internal static class MeetingSummaryFrontmatterFactory
 {
-    private static readonly IDeserializer YamlDeserializer = new DeserializerBuilder()
-        .IgnoreUnmatchedProperties()
-        .Build();
+    private static readonly IDeserializer YamlDeserializer = FrontmatterYamlDeserializer.Create();
 
     public static async Task<MeetingArtifactFrontmatter> CreateAsync(
         MeetingSessionArtifacts artifacts,

MeetingAssistant/Summary/MeetingSummaryTools.cs

@@ -7,9 +7,7 @@ namespace MeetingAssistant.Summary;
 
 public sealed class MeetingSummaryTools
 {
-    private static readonly IDeserializer YamlDeserializer = new DeserializerBuilder()
-        .IgnoreUnmatchedProperties()
-        .Build();
+    private static readonly IDeserializer YamlDeserializer = FrontmatterYamlDeserializer.Create();
 
     private readonly MeetingSessionArtifacts artifacts;
     private readonly MeetingAssistantOptions options;