Added Db stuff

src/EllieBot/Db/Models/FeedSub.cs

@@ -0,0 +1,19 @@
+#nullable disable
+namespace EllieBot.Db.Models;
+
+public class FeedSub : DbEntity
+{
+    public int GuildConfigId { get; set; }
+    public GuildConfig GuildConfig { get; set; }
+
+    public ulong ChannelId { get; set; }
+    public string Url { get; set; }
+
+    public string Message { get; set; }
+
+    public override int GetHashCode()
+        => Url.GetHashCode(StringComparison.InvariantCulture) ^ GuildConfigId.GetHashCode();
+
+    public override bool Equals(object obj)
+        => obj is FeedSub s && s.Url.ToLower() == Url.ToLower() && s.GuildConfigId == GuildConfigId;
+}