Update: Text Channel Stuff

Bugs: Files don't work
Bugs: Video In-Line don't work

Added: idk, everything?

RelayShared/Services/ChatMessageContent.cs

@@ -0,0 +1,14 @@
+namespace RelayShared.Services;
+
+public sealed class ChatMessageContent
+{
+    public string Text { get; set; } = string.Empty;
+
+    public string? ReplyToId { get; set; }
+    public string? ReplyToSenderUsername { get; set; }
+    public string? ReplyPreview { get; set; }
+    public List<string>? Mentions { get; set; }
+    public string? AttachmentBase64 { get; set; }
+    public string? AttachmentMimeType { get; set; }
+    public string? AttachmentFileName { get; set; }
+}