Initial scaffold: ytLive C# WPF project

- MVVM architecture (Models, ViewModels, Views, Services, Helpers)
- Models: Scene, Source, StreamConfig, StreamHealth, YouTubeChannel, ChatMessage
- Services: YouTubeAuthService (OAuth2), YouTubeStreamService (broadcasts/stream health),
  YouTubeChatService (live chat polling)
- ViewModels: MainViewModel with scene management, stream controls, chat
- MainWindow with dark theme: scene/source panel, preview area, chat panel, status bar
- Version roadmap: v0.1 (scenes, RTMP, OAuth2, chat, health) -> 1.0

Models/YouTube.cs

@@ -0,0 +1,26 @@
+namespace ytLive.Models;
+
+public class YouTubeChannel
+{
+    public string ChannelId { get; set; } = string.Empty;
+    public string DisplayName { get; set; } = string.Empty;
+    public string ProfileImageUrl { get; set; } = string.Empty;
+    public string AccessToken { get; set; } = string.Empty;
+    public string RefreshToken { get; set; } = string.Empty;
+    public DateTime TokenExpiry { get; set; }
+}
+
+public class ChatMessage
+{
+    public string Id { get; init; } = Guid.NewGuid().ToString();
+    public string AuthorName { get; set; } = string.Empty;
+    public string AuthorChannelId { get; set; } = string.Empty;
+    public string AuthorImageUrl { get; set; } = string.Empty;
+    public string Message { get; set; } = string.Empty;
+    public DateTime Timestamp { get; set; }
+    public bool IsSuperChat { get; set; }
+    public double SuperChatAmount { get; set; }
+    public string? SuperChatCurrency { get; set; }
+    public bool IsMember { get; set; }
+    public string? MembershipLevel { get; set; }
+}